I think you’re on the right track, but I’d like to point out that while physical pain may (or may not) be inevitable at times, suffering and regret are actually

I think you’re on the right track, but I’d like to point out that while physical pain may (or may not) be inevitable at times, suffering and regret are actually completely optional mental states generated by the interpretation of your experience. You get tantalyzingly close to this with your discussion of Stoic philosophy; consider what would be possible if you were also able to intentionally choose your interpretation of reality, and thus which emotions to feel. It is possible.