Stretching! Use a soft rope or even a leg cut from a ruined pair of hosiery. The idea is firm support while doing anything, so as not to bear too much weight. Lying FLAT on your back for leg stretches, calf string and ham string stretches. Keeping mobility in the joints is key. If you can add light weights without aggravating your joints, do so. (But remember, when using weights in your hands or on your wrists, anytime your weight goes out of your view, it's damaging something )

I agree about the breathing. Most honest runners and exercise experts will tell you the main thing is the breath. (They, of course, also get the runner's high.) There is even a type of exercise that is ONLY deep, good, proper breathing. That is what exercise is meant to do in the long run anyway, get more oxygen to your cells. That's what produces the health and weight loss etc.

But weight bearing exercise is good for the strength of bones. But, imo, not at the cost of the joints.

Using hot packs and heating pads after every session of exercise is a must. TC