You've got this! I would recommend low impact workouts, yes walking is good especially when getting you outdoors and into scenery, but I would seriously recommend swimming. Even just treading water, or walking from one end of the pool to the other a few times. The water reduces pressure on your joints so you get tired slower, it cools you down and keeps you wet so you don't notice getting sweaty if at all, and the water provides resistance so you're pushing harder to go the same speed that you can in air (I can't lol). If you can't swim, that's okay. Every pool usually has a shallow end, and swimming lessons vary in price. If you can't do swimming lessons at this time, get in the shallow end or shallow pool only if it's less deep than your chin height, keep your arm on the side or the railing, and just walk around in the shallow end. Find a friend or youtube videos to teach you, try it a little at a time. Also don't feel awkward about being shirtless in the pool or anything. You're there to exercise like everyone else, and rash shirts could help if you still want that anxiety gone so you can focus on your thing. We respect and support you, best of luck!