One of the best forms of exercise that I have found that helped my overally body joint pains (before I found something even better) is isometrics. Isometrics is where you flex the muscle without moving it. You can either hold a weight for time, or hold your body weight for time, or try to move an immovable object.
You can literally experiment and find hundreds of different kinds, but here are a few of my favorites. The lunge. A pullup 90 degree bent arm hang. The pushup hold 1 inch off the floor. The crab hold, belly up, like a table top. Downward dog. A one leg stand. Various one leg stands. A full squat to the floor. A squat hold 6 inches up off your lowest point. The plank. Side planks. Ok, I hate side planks, but, you know, we all have to work on something.
One theory of why isometrics are so great is that they are exercises that have lasted the ages. Another theory for why they are so great is that they don't break down as much muscles, and don't consume as much blood sugar, so the body still has plenty of energy to recover. From my experience, they did, indeed, make my joints feel much stronger.
One of the theoretical problems of isometrics is that they mostly build strength only in the limited range of motion in which they are used. Another problem that I found with personal experience is that if you hold them for too long until the muscles burn, then not only can you get delayed onset muscle soreness, but also, for me, I ended up shortening my muscles and getting more extreme joint pain. I got new pain in my hips from extended squatting, as well pain in the side of my knees, and at the time, I did not know why, but I knew enough to stop the isometrics!
Another of the best forms of exercise that I found that helped my lower back (before I found something even better) was "the five tibetans". An old man of 70 heard I had occasional back pain, and he shared with me these exercises in an email, and wow, I got great results that greatly improved my life. I ended up with nearly no back pain for about 2 years! (Until I found something even better!)
The five tibetans were really great for my spine mobility, because my arthritis was centered on my lower back.
The 5 Tibetan Rites - Do it Along - YouTube
5 Tibetan Rites - The RIGHT Way, Anti-Aging Tip from Ellen Wood, author of "Think and Grow Young"
But I finally stumbled on even better exercises that improved my spine mobility, improved my strength, improved my flexibility, and eliminated pain far more effectively and quickly, and did this so much more effectively when combined with a specific food! Besides, I had pains in more areas of my body than were targeted with the five tibetans!