As a published author, I immediately set a goal to have another novel submitted to my publisher before my first novel was released. Competition being as fierce as it is, I couldn't let it go at that. If I don't keep my slot filled, someone else will come in and take it. That kind of thinking forces me to set goals. The WAYS of setting goals.
Goals are as individual as people.
What works for you won't work for everybody, and only you know if you're letting yourself off easy, really challenging yourself or if you're overextending yourself. There's a story, but an unknown author, that Charlie Brown was shooting arrows into a wooden fence one day. After each shot, he ran over to the fence with a piece of chalk and drew a bull's-eye around the arrow. You're supposed to draw the target and then shoot at it. Let me tell you, that kind of goal is a sure-fire way to shame even the laziest of us.