"It took us a while to believe we could even do it last year," linebacker Connor Barwin said. "But I remember hitting a point in like Week 6 or 7 - 'Wow, I actually feel the best I've felt on a Tuesday in the last four years of my career.' "
Before introducing the plan, Kelly had asked assistant tight ends coach Justin Peele, who had just finished a 10-year career, if today's NFL player would buy into the program. And Peele's answer, Kelly recounted during an interview with Sirius radio in July, was:
"It doesn't really matter what the coach says, it's actually how do I [the player] feel? If Coach is going to tell me that I'm going to be fresh every Sunday and then I'm not fresh every Sunday then we're not going to listen to him."
By December last season, Kelly said, every veteran had said it was the best he had ever felt in the final month of the season. The results were there. The Eagles had arguably the healthiest team and had only six players miss 13 starts over the entire season because of injury. They won the NFC East.
Much has been made of Kelly's sports science program in how it relates to the physical part of game day preparation. But the Eagles, in their practices and meetings, have paid just as much attention to the mental aspect of football.
"I think that gives us an advantage because we're mentally prepared," linebacker DeMeco Ryans said. "Half of the game is being mentally ready for what you're going to see. I think physically if you couldn't do it you wouldn't be here. That's what separates it."
Thirty-five of the 53 players on the Eagles roster return from last season. They know what to expect, having gone through the season once with Kelly. The neophytes are expected to learn from the returnees.
Here is a closer look at the schedule they will repeat this season for at least 16 weeks:
Monday is, technically speaking, an off day for the players. Few, however, take the entire day off after a typical Sunday game.
Many show up at the NovaCare Complex - the Eagles' practice facility - to watch film, receive treatment for injuries, or use the pools for recovery. There isn't an unspoken expectation that players make an appearance, although Kelly does tend to gravitate toward gym rats.
"It's kind of just up to you. They don't really harp on it," center Jason Kelce said. "I think most guys just do it as a default."
Many teams require players to show up for work that day to watch film and make corrections. The Eagles under Andy Reid would have film review and then an on-field walk-through, although he would scrap the walkthrough as the season progressed. Physical activity was limited.
Barwin said that when he was with the Texans the players would jog after the walk-through to begin the process of expunging soreness from the body. Although the Eagles have masseuses on-hand at the NovaCare, Barwin and Ryans said they get massages on their own.
Cornerback Cary Williams, like Ryans, said that he takes advantage of the time away from the complex since they spend approximately 40 to 50 hours per week there.
"I usually don't come in because it's my day to get away," Williams said. "That doesn't mean I'm not working at home, mentally preparing for another week ahead of me, looking at film and getting a head start or critiquing the past game."
The emergence of iPads has made it possible for players to watch film from anywhere. While Kelce said the starting offensive linemen still gather on Mondays at the facility to analyze tape together, the replay is only a few touches away for all of the players.
"That's the beauty of having it. Sometimes there's a play that happened that you really want to see," Ryans said. "You kind of heard the explanation about what happened, but you really want to see for yourself.
"I typically don't get caught up in it too much because sometimes there are plays that are just going to make you get mad all over again."
The biggest difference for the Eagles who played under Reid - and in most cases, elsewhere - comes on Tuesday.
It has long been NFL custom to give players off, but the Eagles joined the 49ers as one of the few teams to practice on Tuesday. The commonly held belief was that players were too sore to run two days after a game.
"I think coming in on Tuesday helps out in two different ways," guard Todd Herremans said. "A lot of guys probably don't make the best use of [the off day], so your soreness probably hangs on for another day rather than getting out here and running around.
"And I think the other thing is that you're able to put the game that you just played out of your head quicker."
For the next five days, players arrive between 8 and 8:30 a.m., when breakfast is being served in the cafeteria.
The first of two mandatory lifts is held in the morning. The defense lifts together as the offense meets and vice versa. Many teams don't have scheduled lifts. In Houston, under the previous regime, Barwin said, players were required to lift three times a week, but were free to choose when.
The Eagles do not break from their lift schedule all season.
"Some teams drop off by the end of the season," said Ryans, a Texan for his first six seasons. "But that's when you have to stay with it."
The rest of the day is spent either making corrections from the previous game or beginning installations for the next. Both corrections and installations occur in meetings and on the field.
Kelly said that he doesn't feel the need to review every play from the previous game.
"With the advent of all the technology they have, I guarantee every single one of our players has watched the game before they got back here on Tuesday," Kelly said during the Sirius interview. "They all have iPads. They all have the games downloaded to them."
After corrections, the Eagles begin preparations for the coming opponent. They install basics such as formations and personnel groupings on both sides of the ball. Kelce and the offensive line, for instance, begin work on blitz pickups and blocking assignments.
The Eagles practice in shells, not pads, and the pace is brisk, not up-tempo. After a practice that lasts around 90 minutes, the locker room is open to reporters for 45 minutes - as it also is on Wednesdays and Thursdays - as players shower and get dressed for another round of meetings.
The length of the day is fluid, but it is generally shorter than the next two and players are home by dinner.
By Wednesday, the Eagles have moved on from the previous game and are continuing their installations, most of them dedicated to base personnel. They're inserting run plays on offense and getting looks from the scout team on defense.
They have their first padded practice and it lasts for approximately two hours.
"Wednesday's probably the toughest day," Kelce said.
The body, in theory, has fully recovered. As the season drags on, though, the pads are replaced by shells. Meetings - full team, offense, defense, special teams, positional - are held throughout the day. The Eagles' meetings are shorter and more efficient than most, veterans of other teams said.
"They're not long where guys lose their attention," Ryans said. "You hit it quick and get out to the next one."
Many of the players say they prefer the quick classes, but a few, like Williams, said that there was a learning curve.
"It's an adjustment, especially when you're going over details. It can be a difference," Williams said. "It's up to us to be a professional when we go outside the meeting rooms and do extra studies."
The Eagles are mostly focusing their installations on passing downs by Thursday. They practice third down, red zone and install blitz packages, unlike many teams that wait until Friday. Shells become the norm for most of the season.
Thursday is also the second scheduled lift. Like Kelly's practices and meetings, the lift sessions are fast-paced and designed to simulate game action.
"You have to be kind of, 'This is what we've got to get accomplished. Here's our opportunity. We've got to go,' " Kelly said in June. "The game of football is four- to six-second bursts. Not everything we do in the weight room [is] always just four- to six-second bursts . . . but we're trying to create an environment where we have a chance to be successful on Sundays.
"There's different ways to train in the weight room, obviously. But we're not training for a weight-lifting competition. We're not training to body-build. We're training to play football."
Over the course of a day, players get about an hour of free time to eat lunch, socialize or do whatever. The Eagles have Axon Sports touch screens set up in various rooms for the players to get simulated practice repetitions whenever convenient.
The coaches encourage use, but it's not a requirement. Williams said that he uses the touch screens occasionally, but that he prefers film study of receivers he will face because an "animated guy doesn't run like Calvin Johnson or A.J. Green."
"I usually just spend more free time in the cafeteria talking, laughing, joking," Williams said. "You still want to have fun here. It's not all business 24-7. When you get that leisure time it's time for you to relax."
The Eagles have their game walk-through on Friday, a day before most teams. Kelly's walk-throughs are different from most because they're longer - around 100 minutes compared with 60 - and they're extensive.
"Ours is very detailed. It takes the physical part out of it," Ryans said. "Mentally, it's a tough day for us because you're thrown into every situation that you could possibly get in a game and you're getting all of that in one practice."
The players on each side of the ball have the game plans and in meetings run through the plays or situations that will likely encounter. For Williams and Ryans, it is their favorite day of the work week.
"Friday I have more time on my own to really do some studying," said Ryans, who calls the plays on defense. "I have the game plan. The coaches have shown us what to expect. It's when I really get to dive in and look at it again even though I've seen it all week. It's like confirmation."
After the walk-through, the Eagles - players and coaches - have a tradition of jumping into the ice pool. One of the traditions under Reid was "Fast Food Fridays," although the meals were prepared on site.
"I called it 'Fat Guy Fridays,' " Kelce said. "We still have good food on Fridays. It might not be on the scale it was with Andy."
The day is a relatively short one and the players are typically out by midafternoon.
Saturday's schedule depends on whether the Eagles are traveling or not, but there is always a practice that involves running while most teams are walking.
"Just our research through science that you need to get the body moving if you're going to be playing," Kelly said on Sirius when asked for an explanation. "We used the same formula when I was at Oregon."
Defensive line coach Jerry Azzinaro, who followed Kelly from Oregon, said that "from a scientific standpoint it's not a unique system." He added: "Olympic athletes have been doing it for 100 years."
But is it unique to football?
"If you go back as far as [former Cowboys defensive lineman] Randy White at Maryland, he used to bench- press the day of the game," Azzinaro said. "I think a lot of people that understand central nervous system readiness understand the procedures to get ready.
"I'm not sure that there's a lot of people that are willing to take the risk to do what's right. As far as what science has shown us, there's only one way to do it."
For home games, practice typically ends around 1 or 2 p.m. Buses for the hotel where the team will stay the night before depart at 5 p.m. The Eagles stayed at the Airport Marriott for years, and did so in Kelly's first year, but they stayed at the downtown Westin this preseason.
When they get to the hotel, after check-in, there are more meetings.
"It's just an opportunity to hit everything one more time before the game," Ryans said.
The Eagles eat together in the morning before 1 p.m. games, and two groups of buses are staggered to arrive at the stadium two to three hours before kickoff.
The meetings are over and there aren't "two-hour pep talks," as Kelly said in June. The players, who have their own pregame routines before warm-ups, know what is expected of them.
For Kelly, who had meticulously planned the week of preparation, there's only "a whole lot of waiting around" until the bell rings.
"Especially when you have to play later during the day," he said, "it's even more waiting around."