There is no one true, perfect recipe for a happy full life. Everyone needs to carve their own path and come up with their own definition of happiness. However, most people sabotage themselves with some common habits. The good news is that these habits are often simple to define and easy to change. Author Gretchen Rubin says three of them are staying up too late, delaying a project after a certain milestone (as soon as you get that raise, or get married, or buy a house), and being overly certain.