I have been doing these for a few years and need to share how much it has helped my knees, hips, and back.
You can do as much or as little of this as you like but here is a video with S sit change overs (front and back), W sits, Cossack squats, and back arches.
If you would like me to break it up, let me know. I am happy to talk through the whole progression.
Worth trying for a few minutes a day. Let me know how it helps.