Discipline or Regret
Jim Rohn said it nicely: "We must all suffer from one of two pains: the pain of discipline or the pain of regret.". And the thing is, one hurts a lot at the moment but brings you joy later, the other doesn't hurt at all now, but brings you unrepairable sorrow later.
Couple this one with consistency.
This is why I write these 'daily thoughts' posts.