By his own admission, Jennings didn't have much of a plan when he first walked into the ABC Recreation Center in North Philadelphia less than 5 years ago.
He simply told longtime trainer Fred Jenkins he wanted to be a professional boxer.
Tomorrow, Jennings steps into the ring for the biggest opportunity of his career when he fights Artur Szpilka in a 10-round heavyweight fight at The Theater at Madison Square Garden in New York.
The bout between Jennings (17-0, 9 KOs) and Szpilka (16-0, 12 KOs), who is from Poland, is the featured undercard bout on the card headlined by the WBO junior lightweight championship fight between champion Mikey Garcia and Juan Carlos Burgos.
The Jennings fight will open the HBO "Boxing After Dark" broadcast.
"The opportunity is definitely great," Jennings, now 29 and in the top five of many heavyweight rankings, said during a media workout session at Joe Hand's Gym. "I try to keep it on the hush, keep my feelings under control.
"I'm definitely excited, but I've got to go out there and do my job. Then all the celebration and stuff can come afterward."
There is no set formula for developing a championship contender. There have been plenty of "late starters" who went on to win titles.
When Jennings first walked into ABC, Jenkins didn't see an age. He just saw a prospect.
"He was 24 years old, but it didn't matter because of my experience as a coach of 41 years with different types of boxers," Jenkins said. "I thought [Jennings] had an edge over most guys who came into the gym because he was real athletic."
But Jenkins wanted to see whether Jennings had the desire to match the physique.
"I pushed him hard right away," Jenkins said, "I put him to the test, because I wanted to see if he was going to come back the next day.
"Some guys, if you put them in over their heads, they don't come back. Bryant didn't just come back, but he challenged a guy who was better than him. He stood up. He didn't back down."
Jennings, who is light for a heavyweight, with a fighting weight of about 225 pounds, has been scrutinized because of his size, but he says the athleticism in his 6-2 frame has allowed him to progress quickly.
"Boxing doesn't really have an age limit, as far as starting, if you are a certain type of person," Jennings said. "Being an athlete all of my life, I just think I had the boost already.
"I came in the game with dedication. I would run those endless miles. The things that a lot of boxers hate to do I came into the game with - the dedication to training, the listening to instructions. I'm not cocky, but I am confident. So I can honestly say that I was a beast walking into the gym."
Pressed on the matter, Jennings said he still can't fully explain why he first walked into ABC, but it doesn't matter, because he had found his passion.
He had a young son, Mason. He worked then, and still works now, 40 hours a week, as a mechanic for the Federal Reserve Bank. After family and his job, it's all about training. Even when Jenkins tries to give him time off, he still shows up to train.
"I wanted to do something and be something," he said. "Not just be on this earth and just living. I wanted to make some good time out of my time on earth.
After 17 amateur fights in an 8-month period, Jennings turned pro in February 2010.
He has positioned himself with a fight that could put him closer to a title shot either against Wladimir Klitschko, who has held most of the title belts since 2006, or for the vacant WBA heavyweight title that was recently given up when Vitaly Klitschko retired.
"This is definitely a step up," Jennings said of being featured on HBO, "but I just look at it as progress. The progress we've made makes me more confident. We're moving along.
"I've only been boxing for 5 years. I think this is just my destiny.
The Szpilka fight is huge, because Jennings is at a stage in his career at which he needs to stay in the limelight to keep things moving forward.
With HBO and Showtime as the mover-and-shaker networks in boxing, a big win in one of their events can push things rapidly.
Conversely, a setback can stall a career. There is a huge difference between 18-0 and 17-1 in the marketing of a fighter.
The great American heavyweight went on hiatus about 2 decades ago. The last American to defend any of the numerous recognized heavyweight world titles more than once was the easily forgotten Chris Byrd, who had four successful defenses before losing to Wlad Klitschko in 2006.
Jennings and 2008 Olympic bronze medalist Deontay Wilder (30-0) are the only Americans ranked in the top five for the vacant WBA title and for Klitschko's WBC title.
A high-profile fight with Wilder could be just over the horizon if Jennings beats Szpilka. It could be for the WBA belt or a title shot.
"If they're praising [Wilder], it is what it is," Jennings said of the quest for the next great American heavyweight. "I won't say that he is not. I'll just say that I believe that I am.
"I know where I stand and I know what I can do. Everything about me after the [Szpilka] fight will be confirmed. I would like to be fighting for a title within this year. That's our expectations, but my only focus right now is winning this fight."