I hear what you are saying and have the same issues - but in different ways. The trick is, I think, to keep doing things that we can and when age or disability puts a twist in whatever this may be then find something new to explore / do or take a different tack on the same path. I have been into weight lifting almost all of my life and now at 67 I can't do what I used to do - shocking! So I still lift but I do so with a different focus and different purpose. Muscle mass is a thing of the past so I now concentrate on tone and hit the cardio hard. I't not the same as with building guns; I get that, but it has a similar bottom line. I try to walk the same path, maybe a bit slower than before with more rest periods, but I have found that by doing so that I appreciate things I have overlooked.