"The reward of a thing well done is to have done it."
-- Ralph Waldo Emerson
Compared to a lot of projects you have started but not is finished. You get frustrated and tired. Ready to start a new one leaving the previous one half baked.
That is why it is well recommended to concentrate on one thing and see through it until it is done. Warren Buffet said, "you can't make a child in a month by getting 9 women pregnant."