It is never wise to tell David Goggins he can't do something.
In the late 1990s, Goggins used to weigh 297lbs. Now, reports the Today Show, he's a US Navy SEAL turned ultra-marathon runner, with aspirations to break the world record for the most pull-ups ever in a day.
The point of the stunt? The same reason he runs ultra-marathons: "I run these races to raise money for fallen soldiers' kids to go to college", he explains on YouTube.
And while Goggins fell short on this attempt, we're certain that isn't for lack of effort: In 2008 he finished a 150-mile ultra-marathon. According the video "Human Machine," Goggins came down with Pneumonia 90 miles into the race -- and still finished.