Paul Theodore knew he could 30 pull-ups in a single set. He didn't know how many he could do in a single workout. But he learned the answer this past Saturday, when he pumped out 2,501 reps in a grueling 15-hour sweat session.

 It was an amazing feat by any standard, save one: Theodore fell short on his attempt to break the Guinness World Record of 4,020 pull-ups in 24 hours.

But his bigger goal was secure: Raising $25,000 for Zoë Watterson, a courageous 17-year-old competitive cheerleader who lives with cystic fibrosis. And that made this workout the most satisfying of Theodore's life.

THE CHALLENGE

Theodore -- who is 5-9 and 175 pounds -- had a simple strategy going in: He would do 6 repetitions every minute until he reached 1,000, and then drop to 5 reps every minute.

"I had originally thought I would get to 2,000 reps pretty quickly, in about 6 to 7 hours, and then battle it out from there," says Theodore, who is the owner of Fit Me Up, a youth and adult fitness company in Westlake, Ohio.

But that was before the problems began. At 800 reps, his hands began to blister. While he used gauze and athletic tape around the top of his palms to fix the issue, the onset of blisters caused an unexpected side effect: "They took my mind away from focusing on my nutrition," he says. "I didn't take my first bite of a granola bar until the 4-hour mark. At that point, I missed my window for properly refueling and there was no going back."

"Then came severe tightness in my left shoulder and right biceps," says Theodore. "The pain was so bad that it took me from 5 reps to 3 reps at the 1,500 mark."

At that point, Theodore took a 30-minute break to shower and recoup.

"Although I came back to my senses, my muscles never did. My biceps in both arms tightened up tremendously and never loosened up," he says. "I fought for the next 6 hours like this, but I realized at the 1,700 rep mark that I wasn’t going to break the record."

THE MOTIVATION

With the world record out of reach and his body shutting down, Theodore could have stopped. But he had a bigger purpose to keep going: Zoë.

Due to the effects of her disease, Zoë has to take 52 pills a day, and has only 50 percent lung capacity.

"Two years ago, Zoë was in the hospital for 5 months," says Theodore. "Her wish is to renovate the floor she lived in at Rainbow Babies & Children’s Hospital in Cleveland, for all the children that regularly stay there. She believes that a better environment will help other patients be happier, healthier, and recover faster." (All $25,000 raised from Theodore’s world record attempt will go toward making Zoë's dream come true.)

Like Theodore, Zoë found a purpose bigger than herself.

So what's your bigger purpose? It's a great question to ask yourself before your next workout, says Theodore. Or before you skip your next workout. Or before you stop early because you're "tired."

Just think about a person who can't exercise, he says. It could be a friend who's ill or injured, a family member who has passed, or someone you read about in the newspaper.

It’s called an "active prayer," and it’s about training for a deeper purpose, and remembering how special it is to be able to move.

"When you dedicate your effort to someone else, you find greater strength and motivation because of it, and you honor that person with your intention,” says Men's Health fitness expert David Jack, who cofounded ActivPrayer, and helped coach Theodore through his 15-hour pull-up workout. "It's no longer about you. It’s about something greater than yourself."

Try it, and you might just make every rep, every mile, every second of your workout more enjoyable and more extraordinary.

Which just leaves one question: Who are you dedicating today's workout to?