Guilt is anger directed at ourselves - at what we did or did not do. Resentment is anger directed at others - at what they did or did not do.
To the degree we're not living our dreams, our comfort zone has more control of us than we have over ourselves.
To overcome a fear, here's all you have to do: realize the fear is there, and do the action you fear anyway.
I see nothing wrong with the human trait to desire. In fact, I consider it integral to our success mechanism. Becoming attached to what we desire is what causes the trouble. If you must have it in order to be happy, then you are denying the happiness of the here and now.