What are your best tips for staying focused and staying on task to finish something?

Think of all of the consequences if you don't finish. Or do everything you want to do until you become so bored you'll have to complete your task. Or give yourself a reward after you complete your task.

The person who utilize the progression principle will keep adding the difficulty of the exercise that he's doing, while the person who does not, will only stay stagnant.  the person that utilize progression principle, will get a stronger endurance because now his body is conditioned to do harsher routines.{the answer was already on verified)