Indoor rowing on a Concept2 rower has been my solution to keeping in shape. I usually row for 30-40 minutes 3 times a week at a low load. It’s a compound exercise, working the legs, core and upper body muscles (87% of all muscles supposedly) while sparing the joints. Also very convenient, no need to get dressed like for the gym or running. It took months to get up to speed with a lot of initial back pain, but the str…
If you haven't seen it, https://rowinglevel.com has tables for various distances and ages. It intimidated me at first (these times are fast!) but reaching beginner and novice when they once felt completely impossible is a good feeling.
> It took months to get up to speed with a lot of initial back pain, but the strength gained has done away with back issues I used to have.
This has been my biggest benefit as well.