We always convince ourselves that life will be better after we get married, have a baby, than another. Then we are frustrated that the kids aren't old enough and we'll be more content when they are. After that we're frustrated that we have teenagers to deal with. We will certainly be happy when they are out of that stage.
We always tell ourselves that our life will be complete when our spouse gets his or her act together. When we get a nice car, and are able to go on a nice vocation when we retire. The truth is, there's no better time than right now. If not now, when? Our life will always be filled with challenges. It's best to admit this to ourselves and decide to be happy anyway.