I agree, don't sit around waiting for the Grim Reaper - if you do, he will arrive much earlier than you wish.
While I'm physically busted up pretty bad, and too damned fat, I still try to stay in shape by riding a stationary bike for a mile or two at a moderate friction grade on a daily basis. I then use some relatively light (5-pound) dumbbells and do 100 curls with each arm while sitting in the recliner watching TV and sipping on some lemonade or honey bourbon.
And, when the weather permits, I head for the upper reaches of Chesapeake Bay where I dock my sailboat, a 33 Morgan Out Island. Hoisting those 80-pound sails up the mast and wrestling with the jib sheets and winches while tacking provides a damned good workout. Unfortunately, the weather during the past 10 days has been horrendous for old codgers with bad lungs so sailing is out of the question right now. Might go Friday, though if the weather forecast holds.
Until my back problems worsened, I tried riding my bicycle a couple miles around the neighborhood on a regular basis, but now, my grandson rides it. I'm just too messed up to do this anymore, though I would love to.
Good luck,
Gary