Swimming is good, I wish there was a pool nearby I could swim in. I never managed to get the hang of floating with my head up -- I can manage the breast stroke, but when I need to rest, I have to hang on to the side of the pool. But its good whole-body exercise.
Membership at a gym was actually what got me started on the habit of taking daily walks. My partner and his friend got memberships, and he saw they had a massage machine, thought it'd be good for me, so I tried it, and got a membership just so I could use the massage machine. Then my partner insisted I go as often as possible so we got full worth of the membership fee -- and the gym is about a half-mile away. So I walked to and from the gym 3-4 times a week, and that eventuality increased to 5-6 days a week. Then covid hit, but by then I was used to walking a mile most days, so switched to walking in the park, and now I walk once a day, every day.
BTW, my partner quickly lost interest in going to the gym, and I haven't heard about his friend. ;D