An important prevention, like diet and exercise, is a good attitude. I believe it is important to make it a priority to live a life that matters to you. Others may suggest channeling creative energies into a field where it is appreciated if it looks like you could benefit from making a career change. However, I'm talking about the larger goal of living deliberately-- in other words, taking ownership of your life.
I realize that everyone has constraints (work, family, and the like), but it is very important, in my opinion, to not feel owned by your constraints. You need to seize the moment, let yourself feel some confidence, and just be autonomous, despite your obligations.
And how to do this? It involves the same three steps that work wonders for any change you are trying to make for yourself:
1) Imagine it →
2) Pretend it →
3) Become it
Brainstorm about it; jot it down if it feels right, and then just pretend that you are the way you want to be. In time, you really will be that way.