It's not just old people who like the hottest states. I don't know if this is still true, it probably is, but the list of the fastest growing US states is dominated by Sun Belt states. It's not just old people moving there.
Personally, I hate hot weather and rarely wear more than a sweater during the winter in the northeast. People see this as odd because it is. Thinner people than me complain constantly about the cold. Most people don't run so running in miserable heat is not an issue. Some who do tell me that they just work around the misery in the summer and love not dealing with snow, ice and cold, for the other three seasons. Everything is air conditioned. Power outages are rare but if it's really a concern you get a generator. As to old people, at some point falling on ice and breaking something is a real concern. It may not be a coincidence that Hawaii has the highest life expectancy in the US. And even if you don't fall there comes a time when you're just sick of shovelling snow.