The Definition of Done

This is an interesting article on defining when you are "Done" to avoid perfection paradox.

Now, even if those three previous conditions are met, there is still one thing that causes people to procrastinate and be overwhelmed: It’s the unfinished work and the fact that they are never 100% percent satisfied to the quality of their work.
When they are unsatisfied to their work quality, they keep tweaking and tweaking the results but they are unable to finish anything. This is a sure way to overwhelm their selves and generate unnecessary stress.

http://www.lifehack.org/articles/technology/what-can-software-developers-teach-us-about-crushing-the-perfection-bug.html