I just have lower back and hip mobility issues and was wondering if maybe it was partially from sitting too much.
100%. Growing up, we had a drafting table that could more or less covert to a standing desk, so I grew up standing to do a lot of school work, etc..... Later I switched to a big fluffy desk chair / standard desk combo because that's what everyone had. I started to get nasty lower back pain after a few years, Traditional exercise helped some, but switching back to a high desk with stool helped the most. It took a bit, but the back pain more or less went away.