Lots of good advice here already but I'm surprised no one has mentioned meditation yet.
I'm type A myself, could give you many examples of how that did NOT serve me well BUT it did allow me to retire from the military on my own terms (at a large cost to family/friends/health etc.) and allow me to control my activities rather than be at the whim of society/debt/lifestyle etc.
I counsel other veterans weekly, many/most of them type A and we talk about the nuts and bolts of transition AND the emotional side, letting go of the ego, working to be at peace doing very little/earning much less income etc. (and I'm in no ways done with this work, as other said, it takes TIME).
Back to meditation. By sitting and taking some time (the calm app is good, Sam Harris MED app is great) it allows me to work through emotional issues, to clarify thinking, to come to terms with concepts/time/death etc.
Meditation and mindfulness is something that you can't "TYPE A" your way through. The harder you attempt to "win" at it, the further away you'll get.
I suggest Walden (I read a few paragraphs a day, no more, it's meaty in thoughts, I've been "working it" for over three months so not trying to virtue signal here...) and other books on mindfulness, stoicism, the TAO, etc. By focusing daily, maybe at a set time, change occurs over periods of months (while also focusing on diet/exercise/relationships etc.).
Lastly, it may simply take age. I've found that it's been easier to "slow down" and be less type A as I've aged BUT, at the same time, I've been working on those things above so maybe it's both factors... who knows.
Continuing to think on your post, I'll add a few specific ideas that might help...
1. Control caffeine. I've found that my usual daily "second cup" makes me more jittery/anxious, less patient. How much Joe do you drink a day? Are you "burning it off" vai the frenetic/type A activity/behavior?
2. Focus on others. Volunteering/interacting with others/elderly/those less fortunate will remind us how blessed we are and help us relax and stop striving so hard.
3. Focus on blessings and realize how much you already have. Ask yourself those "deep" questions like "why am I striving? What is the goal? Is there a finish line (hint.. it's death)? What am I really trying to achieve? What I am trying to avoid by staying busy/strive so hard?". These kind of focused questions have helped me developed answers that I often don't like BUT, allow me to "give myself permission" to chill out from time to time.
Best of luck!