I am 67 and have pain, real pain in my knees on occasion. When you have that kind of pain I don't think that excercise helps but only makes the pain worse. I've tried it. There is a difference in the various formulations of glucosamine, msm, and propriatary blends. My break through using these came when I tried the Knox brand of glucosamine, etc. I noticed an immediate improvement. Knox includes gelatin which is supposed to help lubricate the joints. You may be more familiar with Knox for making the gelatin used in canning fruit jam. I also found gelatin in the vitamen section with all of the other stuff that an old man takes to try to stay young, ha, in a capsule and it is very cheap. As an aside it also toughens up your nails.
I'm out of the Knox product right now and have been using Osteo Bi-Flex as a substitute and it also has hydrolyzed gelatin in it. It has been working OK also.
Fellas, I don't know about you but I want to stay away from joint replacement as long as I can. By the same token, I had a back surgeon tell me to avoid back surgery unless it was absolutely necessary.
Since I've been taking these products I don't have to bear my weight on a walking stick and I can walk to the top of most small mountains without any trouble, while carrying my rifle, etc.
Back when I was 10' tall and bullet proof I laughed at the thought of these problems. Age makes one more cognizant of the frailty of the human body.
I consider myself blessed to be as apparently healthy as I am.
Good luck!