In my experience, the most stressful games are with short time controls. The shorter, the more stressful. It could be a good idea to stay away from blitz and bullet. Daily games are essentially stress free for me, so maybe play those.
Chess and stress


I am definitely NOT a senior, but I can still relate. Chess can be extremely stressful for some reason (probably because of the AI overlords staring down on us and judging everything we do + faster time controls). Not fully understanding the problem, there's probably not much advice I can give, but it's possible that you're getting overly invested into each game and that's making you stressed about the result. Just have fun experimenting with weird stuff and don't take it too seriously.
Also, long distance running is fun! Always good to run into a fellow runner, regardless of differences in experience.

Avoid time control games, play more of Daily chess with 3 to 7 days per move... This will not put you under unnecessary pressure. Wishing you good health.

Hmm. ILL be 87 in December and I don't feel the stress yet. . .
But I only play 3 day club move matches . . . I checked and you aren't in the Geezer Christmas tournament . . .
I had a heart pacer because of fibrillation but I never feel stress. . .
I also bowl in three bowling leagues but my average is only about 160 now, it went down during the virus pandemic . . .
I think you are causing your own stress . . . Play in the Geezer matches they are always 3 day moves . . .
IMHO . . .
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I'm 78, so you young guys may not relate to this.
Everyone knows that chess can be stressful. Recently, for the first time ever, I've been experiencing high heart rates and even afib during and after hard games. Note that I was a long-distance runner for many years, and normally have a resting heart rate of 48-52 bpm. Doctor says I have an exceptional heart, but I havent told him about this "chessing myself into afib" yet.
Falling down dead at the board is not my idea of ending a game. Any one else of you senior players experienced anything similar?