Probably too late for you, but I'm a big believer in the basic barbell lifts: Squat, Deadlift, Overhead Press, Row, Bench Press, and Chin-ups. Do them all with a medium stance and grip, for optimal leverage (wide-grip bench pressing like the powerlifters do will put a lot of strain on your shoulders). I began to have pain in my shoulder in my forties, got my upper back strong by doing weights again. No more shoulder pain. Rows and Deadlifts in particular counteract the sedentary tendency for the shoulders to come forward while sitting for extended periods of time. I found out last year I also have degenerative menisci. Two orthos told me to stop doing squats and deadlifts, but one guy, one of the top orthos in the Twin Cities (works with a lot of the pro athletes here) said nonsense, the lifting has kept the joint strong, and therefore ameliorates the condition. He was right. I had to give up endurance running (subbed with cycling), but my knees feel great with regular lifting.
Check out Mark Rippetoe's books, he explains the concepts and techniques in great detail. It's too bad that lifting weights is so strongly associated with bodybuilders and their pill-popping, fake-tan posing silliness. Lifting weights is the best anti-aging protocol there is, IMO. Doesn't have to be super heavy, just do three sets of five reps for each exercise. Increase the load when it starts to feel easy, or just stay at the same load; for anti-aging purposes, it doesn't really matter.
Also, make sure your shoes don't have a heel. Try to find 'zero-drop' shoes, like those offered by Vivobarefoot. They have some nice dress shoes as well as sneakers. Wearing even a modest heel puts your whole kinetic chain out of kilter and causes problems all the way up to your neck, including the shoulders. If you can, try to walk barefoot whenever possible, that also helps. Heels were invented for riding horses. If you don't ride a horse, and aren't vain about wanting to appear taller than you are, there's no reason to wear a shoe with a heel. Unfortunately, almost all shoes these days are made with a heel, including toddler shoes! Take a bottle and put a pencil under one side. Watch how far forward the top of the opposite side of the bottle goes from this small increase at the bottom. That's what happens to your body too when you wear a heel, and then your muscles have to pull everything back unnaturally to remain straight, creating unhealthy tension throughout the back and knees, hips, and shoulders.