I am only 75, but I find that laying on my back under a vehicle and reaching up to work on something makes me dizzy, almost sick. So, I don't do much of that anymore. However, installing an antenna on the truck, running the coax and control leads, and soldering the HF antenna connector on the coax, mounting the radio, etc. is rather fun. Yes, it takes me twice as long as it did 10 years ago, but that's OK, I am in no hurry these days.
I still have most of the tools I accumulated during my days as a wrench-bender on industrial equipment, aircraft (A&P license), and lawn/garden equipment. Most of them don't get used much anymore; not much call for clecos, bucking bars, and such during my tinkering.
Ah, well, enough rambling on. No, I don't do much actual work on vehicles these days. As previously stated, my mind says "Oh, yeah, I can do that!", but my body says "NO, you can't!"