Jordan covers some hard truths in this post about how working hard on an app doesn't lead to success. Sure, you have to work on an app to have a chance of success, but the tried and true method, at least in other avenues of life, of working hard and achieving success does not work with apps.
I've always said that success means different things to different people and different projects. What's a success to you may not be to another developer. That's OK. The important thing, as Jordan points out, is to understand your 'Why?". What are you wanting to accomplish? Do you have a plan in place to accomplish that? Why are you building this app?
For indie developers, hard work can very well mean close to nothing in terms of downloads.
The Chart That Lies by Jordan Morgan