I've substituted some quiet meditation, lots of grading and two after-school-meetings. Only one of these things actually helped to keep me on an even keel. My hip is much, much better with only the occasional twinge to remind me of my advanced age. The old Sassafras Mama would have been sneaking off to the gym with that little discomfort. The new Sassafras Mama is still sufficiently terrified of screwing up her hip for life.
I think that's called being a grown up.