The solution to this is to not only take care of your health, but to have younger friends. My 94-year-old paternal aunt never had children of her own and her stepsons live in another state, but she is still active in her church and she has younger friends. She is predicting that I will be just like her.
That's not so easy for introverts.
And "taking care of your health" at most only postpones the problem.
Yeah, being an introvert and not belonging to a faith community makes it pretty hard to build a circle of friends. When I lived in a college town I was active in the community theater and made a lot of friends that way, but in a bigger city it's harder to find a community. Not impossible, of course, but harder.
Thankfully I do have that going for me. I have a good group of friends, and some single cousins, close to my age, and we constantly joke about hanging out on the porch, in our rocking chairs. Except the one I couldnít live with, and the feeling is mutual!
But I think Iíll be ok. Unlike a former neighbor. Sheís about 20 years older than I am, so in her late 60ís, with multiple health problems, very limited income, and the best way I can describe her, is very unworldly. She has never lived more than 5 miles from where she does now, has been her same apt for 40+ years, and my former landlord, who is still hers, is contemplating selling. I have another friend who still lives there as well. The problem is, Sue, as Iíll call her, seems to think that when/if the house is sold, the new owner will continue to keep it as a rental property. The problem with that is a. the house is old b. Iím not entirely sure all 4 apts in that house are legal, and c. very little maintenance has been done. Its basically only good for a teardown.
She has some family, but not close, and very few friends. Her world is very small. My friend who still lives there told her about the possible sale, and suggested she might want to apply for low-income senior housing, for which she would qualify, but there is also a waiting list. she has chosen to bury her head in the sand thinking that he wonít sell, and that the new owner will keep things as they are, which really is the most unlikely scenario. Its kind of sad really, but you canít force someone to do anything.