My dad was 42 when I was born, and he was keeping up with me on hikes in my early 20s (his mid 60s). I haven't done much hiking with him lately, but he's going on 50 mile bike rides at 70.
I think having kids late can help people stay young longer, if you let it.
My goal is to keep up with her mountain biking, snowboarding and hiking for as long as I can. Hopefully I’ll be on the game well in my 60s and her 20s