So far, I am lucky. I am coming up on the septuagenarian birthday in a couple of months. My only real complaints are that my equipment is stored in the attic and it takes me a couple of trips to the car to get it loaded. I could keep stuff in the barn for a first floor carrying experience, but the barn roof has begun to leak, and my wife, who wants to move (so do I), says it's the next guy's responsibility to fix. I use the old Berg HT112, EX112 mini stack coupled with Genz Shuttle 6.0 or NeoPak 3.5. Not really very heavy, nor hard to move. I use a Rock N' Roller cart. As of now, I can easily stand a whole night with any of my basses, the heaviest being the one I use most, Roscoe Beck V. I do, generally, sit when playing upright, an old 1939 Kay, but that is more for ease in bowing than anything else. I do sit while playing in pit orchestras. I enjoy playing musical theater more than anything else. Not only for the challenge, but the fact that I'm usually finished by 10 -10:30 PM, and only have to pack up at the end of the run. I'm really losing interest in playing bar gigs that don't finish until 1:00AM. I don't relish driving home late at night. The biggest age-related thing I've noticed, so far, is that I tend to sleep in the morning after a gig, and don't get a lot accomplished the next day. I used to be able to get up the morning after even a late gig and not think anything of it. I have been reading from charts and scores for decades. I don't really know if my ability to memorize has been compromised. I keep fairly active, and bicycle about 2000 miles per year, but now keep to bike trails and the canal path after a real close call being hit by a car driver on an early Sunday morning bike ride in Napa a few years ago.