-- My dizziness was due to super tight jaw muscles due to TMJ due to habitual clenching. I fixed (or rather improved) that with "The Quieting Reflex" by Charles Stroebel. I still get a tight jaw, but not nearly as bad as before.

-- For diaphragmatic breathing, I learned that earlier from meditation books and martial arts classes, but:

-- I have trouble breathing through my nose due to deviated septum, swollen turbinates and nasal polyps. My scalenes often engage automatically to assist with breathing. I catch them kicking in as I fall asleep for example. I think I will have to get my nose fixed to get rid of this.

-- For posture, I've used "Get it Straight" by Janice Novak, "Somatics" by Thomas Hanna, YouTube videos and blog posts. I also had a chiro examine my posture and describe what he saw which was useful.

-- Another good source on posture and stress is "Somatics" by Thomas Hanna.

-- I've started reading the SaveYourself.ca ebooks, hoping to master the art of working on my own neck muscles. The material is interesting, although much wordier than it needs to be.