I have done 45 to 60 minutes of pool lunging when I can. You need to find a lap pool that is not too deep. The pool I use now has a deep end so I lunge for 60% and breast stroke the rest. Water shoes help to get traction if the pool has a tile or smooth bottom. It can be a great workout without any impacting. I can do about a mile in an hour.

I'm out of the pool until PT clears me to return after recent shoulder surgery. Breast stroke is a great exercise for bad shoulders. As you finish the stroke, pinch the shoulder blades back and down to strengthen the muscles that join at the rotator cuff.