All our successes are the same. All our failures too; We succeed when we do something remarkable; We fail when we give up too soon; We succeed when we are the best in the world at what we do; We fail when we get distracted by tasks we don’t have the guts to quit. — Seth Godin, in The Dip.
The Dip is a little book that I found the other day by chance in a nice bookstore in the Dupont area. The book basically teaches you when to quit or to stick to a project, mainly professional, but you can apply it to anything in life.
The idea is very simple, you should identify what really matters (and he tells you how) and then focus. Quit otherwise and ignore the rest. Personally I found the book pretty inspiring although I disagree with the author in some of the examples he gives; you can even say the little book is too long at times.