For me being the Fps Doug that I once was while still retaining a modicum of hair I have long since moved away from the truly sweatfested titles such as R6: Siege, CoD, CS, Valorant all that shite and now find much lighter noted games such as Halo Infinite and Darktide to be more my bag...ok perhaps not the latter in terms of being light gaming fair I mean - you should honestly hear us all panting and thankful it's over with after we complete a mission together.
My biggest issue in my middle term years nearing 53 is that my index finger over the years has taken on the form of, well a dick. It's become slightly bent out of shape and has quite the prominent head adorning it at the top and can often completely seize up on me during a match meaning I have to release relax crack it and continue to pwn noobs and yes I'm not kidding at all about said appearance. My entire family make fun of it on the daily and I do not care, I know what it's capable of. Another thing on top of this is how I've become so incredibly sensitive to sound, and I'm not talking about the game sound coming out of my pebbles I'm talking about how moving my mouse can sometimes make a wire on my desk keep making a tapping noise, and it absolutely infuriates me no end. I have to stop and find the source immediately. I'm not angry person by any means but fuck me having certain sounds suddenly capture your holes when trying to concentrate on a game.I would say my reflexes and timings have slowed naturally, but there has been many a time I can and sometimes do surprise myself pulling off that 'sick' grenade or whatever and shaking my shoulders and propping up the middle finger letting out a hallowed burley FUUUUCK YOOOOOU! in an act of pure defiance as I did in my twenties. I'm happy that I can still hold my own in an online ruckus of the more slowed variety anyways. Just being part of the winning team is enough rather than trying to showboat constantly as I once felt was always warranted.
On top of this my eyesight, you know you're in trouble when in a game and suddenly a plethora of brightly colours appear akin to one of those old tin based kaleidoscopes in your peripheral vision and refuses to go away. I've had to go from my normal 1.25 to 1.50 and hopefully never have to go beyond and is clearly as I can see everything represented if I then take them off and get in bed with my phone in hand I can't see a damn thing. Perhaps gaming has played its part, but doing artwork for so long surely has been involved too. Do get your eyes checked chaps.
Ah yes, the pissing test. I've lost count of the amount of times I've had to make it through something I can't just really up and walk away from leaving my team in the shit because my bladder is intent on being emptied constantly. The irony being that during most if not all my time spent with the guys on Darktide the very first thing we resign ourselves to on a break is to get more drink. I know that you know that we all have to now get up in the middle of the night bladder near rupturing only for it to let out record scoring amounts completely countering the amount that you drank that day, but having that happen during a match where leaving once again could end up with a team wipe, yes not the best.
Another would be a more common symptom which is back pain, last year I finally gave up buying into all those fancy smanshy dedicated gaming chairs (that snap in half at the base if you own them beyond six to seven months) and settled for a much comfier much more embracing to me at least camping chair - not only do I no longer feel as though I'm constantly welcoming piles, but the allowance of more flexible natural movement has really made me never look back on ever buying a chair of any sort ever again to be fair. There are no doubt downsides I'm yet to recognise, but for now, I'm extremely comfortable in my blue fishing style ass holder far more than I ever was sat in a chair for overly long periods.
So again, gaming in your later years. Share what you like, hold in what might make you look like someone whose finger after years of mouse scrolling and not using auto-roll is now in the shape of a helmeted penis and gets mocked incessantly.
And what do we say to old age?
I AM. I GAME.
It's sad when you realise it's no longer a case of getting back to speed with something, but that you've lost it and it's never coming back. Well, not unless I make a deal with the robot devil to get new hands... 
