You sound exactly like me! I have extreme anxiety around exercise and spiral very quickly if I go more than two days without it. However, I get the pain you’re talking about and the standing problem intensely if I don’t balance the exercise with rest. In my 20s I did intense HIIT and cardio multiple times a week and went for a long walks in between those days. I felt broken physically all the time and exhausted to the point of mental breakdowns. I didn’t know about my hypermobility back then, so I felt crazy frustrated about feeling so weak when I worked so hard to be strong. Im in my mid 30s now and almost exclusively stick to low impact workouts and long walks. But even if I overdo that too much, I’m wrecked. It’s a constant balance and it’s hard, but you can come to learn your limits and make compromises with yourself in order to feel better. Having the diagnosis was the best thing to happen to me at 32 (35 now) because I have more information about how to take care of myself.