Discipline is freedom.

Discipline frees us from the bonds of slavery to a merciless master: seeking pleasure and avoiding pain.

 When we are undisciplined and "blow-off" our homework, our diet, our exercise or (fill in the blank) in favor of some instant gratification - we set ourselves further back from realizing the true joy - the goal.  The more we avoid the initial "pain" of the associated discipline, the greater the burden we carry around daily.