>> cool. >> come on, alex! that's your challenge. you can do it. >> if he falls off the wall, he has to do 30 burpies. >> nice. >> no the monkey bars. >> this is the hardest part of the challenge. he's doing -- look at him. >> i asked one of the guys, is that a good idea. he said only if you want to dislocate a shoulder. alex, you can do it. >> how big is that? >> 400-pound tire. >> boom, boom, boom. didn't even slam it. >> good job, alex! >> woohoo! good job! [ applause ] >> world-class time. >> that's the time to beat. >> that's the time to beat. >> that's the time to beat. >> we can totally do that. >> when we come back, we're going to give it a shot. >> don't go anywhere. >> get the oxygen ready. ♪ >> get the oxygen ready.