What's with the Fear Factor?

Today I FINALLY finished a painting I was working on for several weeks now. With some mediums, several weeks is not unusual, but watercolor is a quick medium. (or supposed to be) You either get it right or you don't. I really liked the start of this painting and was afraid to finish it because I was afraid to ruin it.
I keep telling myself, "it's only paper and time," and "every painting is a learning experience," yet the fear factor creeps in preventing me from going forward.
Well finally, today I pushed ahead. And really, there wasn't much more to do. I only had to add the darks. I am still happy with my painting but I need to overcome this fear that often creeps in, leading to procrastination, preventing me from going forward.
I know I am not alone with this problem. Any insight?

9.25X11 Arches 140 lb cold pressed