My father was very active well into his 80s, going for 10+km bike rides almost every day, until he got heart trouble. He would still walk for hours every day, o

My father was very active well into his 80s, going for 10+km bike rides almost every day, until he got heart trouble. He would still walk for hours every day, often taking the stairs up the local hill, 400+ steps. He still got Alzheimer's. A lighter, later case than he would otherwise had, I'm sure, but still, he doesn't remember what he said 2 minutes ago, asking about the same things over and over again. So while there are lots of excellent reasons to stay active into old age, it's not a replacement for treatment.