All Might Remembers Why He Fights In My Hero Academia

“If you feel yourself hitting up against your limit, remember for what cause you clench your fists! Remember why you started down this path, and let that memory carry you beyond your limit.” 

When you face an insurmountable challenge, keeping your motivation at the forefront of your mind helps you progress. Superhero All Might pushes himself to the limit daily - he definitely follows his own advice. In All Might mind, the limit does not exist.