Commitment

From the book Flow (about relationships but could apply to many other things):

regardless of any problems, obstacles, or more attractive options that may come along later, one is freed of the constant pressure of trying to maximize emotional returns having made the commitment… and having made it willingly instead of being compelled by tradition, a person no longer needs to worry whether she has made the right choice, or whether the grass might be greener somewhere else. As a result a great deal of energy gets freed up for living, instead of being spent on wondering about how to live.