Two things that really helped my balance when getting back in the saddle as a grown up were to ride in two point/half seat, focusing on getting my heels as deep as possible so that I could break the knee-pinching habit and also dropping my stirrups, again thinking about letting my weight fall deep into my legs as well as staying loose in my lower back and hips (posting the trot without stirrups was good for me to stop pinching with my knees, actually) I did/do this at all gaits, especially in the spring when I’m trying to get my legs and seat back after a winter off. I went from a short strided, choppy guy to a mare with a very ground-eating stride; she felt SO much faster than my gelding at first. Lots of half seat for strength and and lots of dropped stirrups to get myself deep in the tack helped me get more used to her way of going and be stronger and more confident in my balance. It’s hard to come back as an adult; we don’t bounce off the ground like we used to! The sweet, patient ponies are a Godsend for us!