Two (unrelated) suggestions, from personal experience:
See a psychiatrist. There may be a chemical solution.
Go out of your comfort zone. Sign up for intense martial arts classes, and don't quit after you come home bruised from your first session. It will not take long to overcome pain thresholds. Mental pain/aversion is not the same as physical pain, yes, but the skill of breaking past aversion limits is transferable. There's a reason for the saying "pain is only in the mind."
As an experiment, here's a thread for people to post about things they care about. Specifically, for things that are possible to contribute to, in some way, and preferably, to invite others to join.
Mine is buying and donating highschool textbooks to schools in the 'grey zone' of Ukraine (where the war kinda isn't fought, but few people would be surprised if it started.) I don't deliver them myself, though.
What's yours?