I am currently in peak hunchback phase but previously I've done well with both gym (super simple jog + upper back and shoulder machines) and yoga. Yoga I like because it builds strength but if taught well also helps your nervous system so you aren't holding on so tight. I've not been back to a studio since they all got so expensive after COVID but there's good YouTube stuff. Yoga with Adrienne is probably the most popular absolute basics and she usually has a 30 day challenge in Jan.

Edit for spelling