Suddenly, I wasn't thinking of my creaky knees, my achy back and my red, sore feet. I felt sick and sad for two people I never knew who also were just trying to cross the finish line.
Jeffrey Lee, just 21, collapsed moments after crossing the line. Lee finished the half marathon in 1 hour, 58 minutes, 6 seconds, at a 9-minute pace, according to the event's website.
Lee, a University of Pennsylvania senior from California, was in the undergrad program at Wharton while also working toward a master's in nursing, Penn spokeswoman Phyllis Holtzman said.
"It's devastating," Holtzman said. "We're all still trying to process this. His family is on their way here. The campus will be crushed by this."
The other man who died was 40 years old. He crumpled to the ground a quarter-mile from the finish line, according to police. His identity had not been released as of last night.
Both men apparently had suffered heart attacks. Both were pronounced dead at Hahnemann University Hospital.
I wondered if I'd seen those two men during the last six months, when my training runs took me along Kelly and Martin Luther King drives, hugging the Schuylkill in what runners call the "loop."
Before dawn yesterday, were those two men near me when 25,000 runners walked toward the starting line on Benjamin Franklin Parkway? Were their friends and relatives on the sidelines holding signs or giving runners high-fives?
The weather conditions were perfect. Few of us feared dehydration or heat exhaustion.
Marathon deaths are rare. Fewer than 1 out of every 100,000 marathoners die from sudden cardiac arrest during training or racing, according to a study by the British Journal of Sports Medicine.
But each death hits us in the gut. In last month's Chicago Marathon, a 35-year-old firefighter running to raise money for burn victims collapsed 500 yards from the finish line and was pronounced dead two hours later. Also last month, a 27-year-old man died in the Toronto Marathon.
Three runners died in the 2009 Detroit Marathon in a span of just 16 minutes. Two collapsed between the 11- and 12-mile marks; a third went down just after finishing the half marathon.
And a 28-year-old runner died in the Boston Marathon in 2002.
Few runners can forget that Jim Fixx, author of 1977's best-selling The Complete Book of Running, dropped dead during a run at age 52.
In Philly, City Councilman John B. Kelly Jr. died in 1985 while jogging after a row on the Schuylkill. Kelly, an Olympic rower and the brother of Grace Kelly, was 57.
None of this stops die-hard runners. We point to all the sedentary people who die holding the TV remote.
But marathons are brutal. Training takes a toll. Some days I've run the same hill eight times. Other days, I've sped around a track or done interval training on the street. At times my stamina is shot, yet I force my beaten legs and blistered feet to finish.
I've endured almost every injury - even two stress fractures in the same foot, when I had to hobble around in a boot. Still, I run.
My first marathon was in Philly in 1996. I reached Mile 22 when ambulances started to pick up runners who couldn't go one more step. I saw other marathoners step off the course to vomit. Blood dripped down the shirts of men running near me.
I felt terrible. My legs throbbed. Every muscle in my back ached. My head pounded. I promised myself I'd cross the finish line even if I had to crawl.
As I wiped salty sweat from my forehead, I staggered. I had hit what marathoners call The Wall. A tall, lanky man with 40 marathons under his belt came out of nowhere. He told me that he'd been waiting for his friend at Mile 20, but the friend didn't show up. He asked my name and made sure I was coherent. He told me that he'd help me.
"You're going to run to the end, Barbara," he said. "You can do this."
I asked him how far I had to go.
"It's just around the corner," he said.
"I'd never lie to a marathoner," he said with a smile.
Tears came to my eyes. I saw flashes of my life - just the good parts, like the moments my son and daughter were born and I could hold them for the first time.
I turned to the man making me push ahead. I thanked him, over and over.
I never saw him again.
Every marathon has moments you never forget. And last night, I couldn't stop thinking of the two men who died running down a dream. I imagined the deep pain that their relatives and friends must feel.
Last night was supposed to be a time to celebrate, not mourn.
I don't know exactly why or how they died.
But I understand why they were out there.