 On a similar note, a reporter once asked Muhammad Ali how many sit-ups he typically does in a workout. Ali's answer? 50. The reporter was taken aback, surprised that it wasn't much more. A champion heavyweight boxer surely can do more than 50, right? Ali explained it was 50 because he only started counting after they started hurting. The ones before the pain didn't even register there. Muhammad Ali understood the power of stress. Ali was right. The reps you do after the burning starts are the only ones that matter.