"Doesn't work" for me has had different meanings. Most of the time I start because I feel initial passion for the project. Then, positive user feedback fuels me

"Doesn't work" for me has had different meanings. Most of the time I start because I feel initial passion for the project. Then, positive user feedback fuels me to keep going. Things go well (more users, good feedback, sales), it's easy. Things don't go well (no user growth, no feedback which can actually be worse than bad feedback, declining sales), I feel terrible. Do I want to keep pushing through the tough times? That's the test for when to give up.