So I will tell you that the intention and purpose of mindfulness is not to be thinking more deeply, but rather becoming more aware of the process as it unfolds; to become more aware of your thoughts, feelings, and emotions, whatever they may be without judgement or avoidance. I highly recommend Jon Kabat-Zinn's Full Catastrophe Living. It has a nice mix of theory and exercises that have helped many people.
I am an intern working to promote Amit Sood's program in my local community. Our group is working diligently to spread his work as far as possible, including in local businesses and social centers. It really helps general happiness to pay more attention to details, embrace the moment, and get out of dark loops within ourselves.
The cover and title are kind of tacky and I haven't read it yet, but a therapist told me about IFS a while back. Might be worth looking into:
http://www.amazon.com/Self-Therapy-Step-By-Step-Wholeness-Cutting-Edge-Psychotherapy/dp/0984392777
Ben Behind his Voices is a book about a mother's son who developed full-on schizophrenia by the time he was twenty or so. Most of his early symptoms (starting in high school) looked a lot more like ADD or depression.