Okay, it happened. Of course, don't deny that it ever happened. Analyze why you made the mistake. Put your energy back into it. Learn from it, and undertake never to do it again.
Life is good.
Now move on. It's because you weren't serious enough about your commitment. Apply this idea to the greater goals of living. Realize that if you don't get started today, you may never do it. Even if you don't have time now, at least write down the good ideas before they become lost forever.