One requirement behind exercising discipline involves consistent practice. A word or two about practice: in my experience, practice does improve skill, but does not necessarily make perfection. We all remain human and, even in our expertise, fallible.
Practicing consistently, however, does insure that you will develop skillfulness about whatever it is you're aspiring to do. If you practice consistently, a few minutes every day, at anything, you are more likely to succeed than if you cram.
Overtraining, at least in terms of physical sports, can prove dangerous and even deadly. So the key here is: practice with practicality, with consistency, with moderation.
Sometimes discipline involves excessive training. There are times when we run up against deadlines and the clock is ticking. But, for the most part, the skills that we develop by practicing a little bit every day are the ones that eventually mean the most to us, and to others.
This is why systems like Gong Fu originated from the idea “to perfect through practice.” The skills that you gain through applying yourself, a little at a time to a task every day are the ones that grant you the greatest satisfaction. It's sometimes called “paying your dues.” I prefer however, to think of personal aspiration not as something owed, but something received instead. You can bank on that anything you desire to achieve or acquire is planted into your heart for a purpose. The way you choose to explore or develop that skill is life's gift to you.