I loved swimming, when I first started I could only do 2-3 laps but it didn't take long before I was swimming long distances - and I could see it in my body profile, less gut, leaner body. I was actually starting to look like a swimmer.
When I lived in SoCal they had a rock pier at Newport Beach SW of John Wayne airport and I'd run the rocks. Not good for the joints but great for balance and leg strength. I miss that... But as a kid I played so many hours of basketball on concrete courts its a wonder my knees still function. My right hip is in bad shape, but thats probably from decades of golf.