You are describing a universal problem. Its called a midlife crisis and no type is immune. I've been teaching for 15 years and I am in a profession that is suited for type 6's. But her I am tired of this shit. You're looking at your current predicament as if your type is the problem, when its the solution.

Books to read, physicial activities to do, mental exercises to practice, conversations to have with family and friends, etc.?

Do them all. Read a book. Any book that interests you will work. I like historical fictions and am done with books that help me analyze myself. But thats me. Go exercise. I simply go to gym and do some cardio, everyday. Something about 9's tells me you should hit the weights or do some yoga. Ignore your number and just go be active doing whatever suits you. Meditate to help you find a calm state. Take a class or even yoga / tai chi type exercises. Talk with your intimate friends about life and find someone who you can unload on.