I did two rounds at a chiropractor years ago after injuring my upper back trying to remove a fallen tree (also had sciatica issues for a while previously) and after doing his magic told me to pull my shoulders back and down while squeezing my sides at my elbows to help with the upper back pain, and to hold my leg at a 90 with my ankle resting on my opposite knee while pushing down on the knee of the crossed leg for my lower back/hip joints. Previously, I couldn’t stand in place for more than 20 minutes without severe pressure on my lower back and had numbness in my arm from the upper back injury, but both have completely stopped since then.