I feel successful when the writing goes well. This lasts five minutes. Once, when I was number one on the bestseller list, I also felt successful. That lasted three minutes.
When you promise yourself something, make a commitment, you can't give up. Because, when you're in the gym, you have to fulfill the promise you made to yourself. The people who can self motivate - in any field - are usually the ones who win. Regardless of talent.