Who wants to live past the point where other people are changing your depends etc... I have seen people live past the point where in a normal society, they would have died a natural death, they were miserable but clinging to life, completely dependent on others and I think I mentioned... miserable. My dad made the best of life. His main diet was whatever he wanted he ate Big Macs and fries, went to Chinese buffets well into his 90s, he did eat turkey bacon, I don't think it made a bit of difference, he died a few months past 96.
Mom on the other hand spent the last (almost) decade of her life blind and with dementia. On a lot of medication and had "sundowners" she would sometimes keep dad up until 5:00AM looking for something, she didn't know what she was looking for but she had to find it. You couldn't stop her. She didn't eat a lot in her last years but when she did she ate whatever she wanted as long as it was good. Someone got them "meals on wheels", it was bad... they would keep the milk and feed the food to cats, foxes, or whatever came up to eat in the yard. I thought it was a bit of an abuse but they did what they did. Oh.. and in the last few years dad ate several bags of Hershey Kisses per week, he would eat them all day long. In the last few years he had a catheter and would get a UTI about twice a year, he HATED to go to the hospital and would rather have stayed home to die every time but my sister (the nurse) would have none of it. She got him kicked out of Hospice twice for going over their, and his, head and sending him to the hospital.
Moral? It really don't matter that mush. Genetics matter. Exercise don't even matter very much, if at all. He had three or four angioplasties?, where they put a balloon in the artery and inflate it to fix a blockage. He walked every day once he was diagnosed, still had the blockages. Finally he had a triple bypass, the carotid artery cleaned out, and a pig valve put in his heart. He lived 20 years +/- after than with no exercise and no more problems.
We don't live that log here no matter what we do. 70 years? 80 years? 90 years? Some a few years less, some a few more. I say enjoy your life because you are NOT going to hold on to your strength or your life in the end (there are always outliers who enjoy good health until they die of old age and ones who have bad health years before they die).
Enjoy your life, don't make yourself miserable trying to have just a little more of what by that time will likely be the most miserable time of life, with pain and problems, with things that don't work right anymore... it is going to happen anyway.