I got a lot of muscle back with TRT and training with resistance bands over the past year. All my health problems are orthopedic and I was rehabbing after rotator cuff surgery in 2015 with bands and decided to give them a try to build upper body. I also had hip replacement 2006 and can only bike on the air dyne because I am fighting off the other one needing to be done.
Joint pain can be fixed. Bands enable one to train pain free and there are some good training options with them. Very fortunate to not have systemic things going on at my age.
And, yeah, it does feel good to be able to take off your shirt and get double takes at age 63.