I’ve had TMJ since my teens. While the likelihood of health problems may increase as you age, there aren’t certainties. A lot of general health is related to lifestyle. I’ve also had the heartburn problems since my mid 40s (I think partly due to a hernia and partly due to bad gut health. Eating probiotics helped a lot.)
Of my four grandparents (all of whom I think lived into their 80s), the two who never gave up smoking cigarettes (heavily), had severe health problems and a lot of pain. The grandfather who had smoked mostly cigars and given them up decades earlier (50s/early 60s?), had a heart attack when he was planting trees in his yard.
My parents are in their 70s. My mom had a terrible stroke in 2021 and it was basically a miracle she survived. While she had a terrible year, through the grace of God, the support of my father, and incredible hard work (she’s a formidable woman), she’s pretty much made a full recovery (just a slight tremor in one hand when she gets tired). She travels, drives herself around town, plays the piano, visits friends, crafts, walks over a mile a day, and does what she wants to do. I’m pretty sure she’s in better shape than I am at 51.
My father is slowing down some, but still leads a full life. He can no longer lift heavy things, and probably has to hire people for home/yard maintenance and repair he would have done previously. I don’t think he misses mowing the yard, and considering his handyman skills, the house is probably better off in tge hands of a professional. Meanwhile, last November, he drove my mom 900 miles for a holiday in Vegas and then 900 miles back home.
My ex-father-in-law is in his 80s. I think he’s slowing down a little now, but until recently, he was cycling (a lot) daily and would travel around the world scuba diving.
My ex-mother-in-law, unfortunately passed away several years ago in her 70s. She had been leading an active lifestyle, including playing tennis, being an avid gardener, and visiting us from Georgia every year.
I think you can have a high quality of life in your 80s. While there are, of course, a myriad of interacting variables, I think if you avoid smoking, minimize alcohol consumption, and have daily exercise (this is where I fall short) to maintain bone density, muscle tone, and cardiovascular health, your chances of having “golden” years rise significantly.