Have you ever had a job where your boss yelled at you if you weren't continually working? If not consider getting a part-time job at a fast food restaurant where you work maybe one day a week for eight hours at a time. Fast food restaurant managers are quite skilled at motivating (and please forgive this word) "lazy" youths.

Think of willpower as a muscle. And think of the fast food manager as your personal trainer.

My guess is your problem arises from never having had to stay up all night doing homework that you found boring, pointless, tedious, and very difficult.