I understand what your saying; I have been down that road and feel better today for a couple reasons. I will share a couple stories with you. First, these are some of the best comments and heart felt recommendations I have read anywhere. Second, Bill C. is right on.
In 1998, I had a bad car accident when another driver failed to stop and pulled in front of me. I hit the front 1/4 panel of his 3/4 Ton truck at 45 mph. Thankfully, I was wearing a seat belt, but was still knocked-out and ended up with neck and shoulder problems. Consequently, I missed a few years because I could not shoot without pain. Exercise and stretching helped and eventually was able to shoot again.
In 2004, I injured my right knee and it would swell up at the thought of exercise. After 1 1/2 yrs it started feeling better, but something happened and it swelled up the size of mellon. Then someone suggested taking Glucosamine - Chondroitin which helps repair joints (according to some sources). It worked and my knee better within a month, but I lost muscle and strength in the legs from not exercising and being as active.
I am back exercising, walking, jogging, biking, weights, stretching and shooting more. I still shoot 54 - 70 lbs and regulary with 66#. I use the heavier weight for conditioning. At 67 I still look forward to bird hunting with my dogs, big game hunting, and fishing. I feel better and can to do things with the kids and grandkids. Staying active is a blessing.
One more story. After my mother got cancer, my dad became less and less active. During the last 15-20 years he was inactive. He loved camping, travel, hunting and fishing. Eventually it was hard to get him out if there was a game on the TV. I decided that was not for me. I would walk rather than sit and read before watching TV. Because I did not live close to dad, I could see a change taking place each time I visited. His problem was not staying active when he could. He lived to be 87, because he never had any health issues and was blessed with good genes. He just hated exercise and aging finally got the better of him.
As others have said, it is a good idea to get a physical before starting on an execise program, and find a personal trainer to help you get started. Hopefully, you will avoid injury, strains etc if you do it right. The body will respond if there is a fire burning. It is still not to late to get started. Good luck Bill.