Excitement will get you going, but it is not enough to keep you going. Excitement, by its very nature, wears off. Beyond the initial excitement, success requires commitment. Commitment keeps you going long after the novelty has worn off. Excitement begins the process of achievement.
Commitment sees it through to completion.
Excitement is a reaction. Commitment is an intentional decision. Success occurs when you're able to transform the energy of your excitement into a solid and lasting commitment. That's not easy. It takes effort.