I'm also getting up in age (57) and I use to have a really bad right knees years ago in my 30's, which I first noticed on my first 1,500-mile bike tour. A doctor told me I'd eventually have to get surgery. I've yet to have surgery and instead got into weightlifting to strengthen the knee. I still have issues, but my issues come from doing stupid things, i.e. overdoing it. And when I do, I keep looking for exercises to help rehab my knees. However, the foundation are squats and deadlifts. Doing high reps with light weights are good for building a foundation, but if you want knees of steel you need to work towards heavy weights. This helps to balance out the strength of all muscle groups, that one activity cannot, such as cycling or running....

Some good resources, but many others available.

Good 3-minute introduction to importance of strength training



Myth busting that so many repeat about us old guys lifting weights.