One thing I can agree with is that if one is stressed out and have poor psychological habits you will suffer and be miserable regardless.

I would say focusing on mindfullness(like vipasaana) can go a long way in this. But mindfulness is not an intellectual exercise, one has to live it. Do multiple hours of meditation a day and it gets you somewhere good in a few months.

I can actually tell you how to do this right now. Take a 10 day vipassana course and practice the recommended two hours a day. If you use only therapy, seriously follow the therapist, but do some meditation too.

Once you do this, you will soon develop Attention(Concentration) and Equanimity(Inner Calmness in the face of tremendous external circumstances).

Soon you start realizing some inescapable facts:

1. Your current moment is ever changing.

2. One attaches more of the self(the ego, I me and mine) with the past and tries to predict his state in the future and ends up miserable. Don't think with the I, you are bound to suffer. The right action is timeless and free of the I. This is the reduction of the ego.

3. There is tremendous joy in focusing on being present in the moment. If you are into running and all you are doing is taking joy in your feet, breath and posture all the time for 5,10 miles you know what I mean.

This is the key to everything. No amount of book reading on self improvement can get this to you