When I was younger I would have said 30+ years was considered old as well— I feel like it's kind of common among younger kids/teens to have this mindset, but as you get older you kind of realize that that's not old at all lol. I'd also agree that 70+ is what I'd start to consider as old realistically, and even then I sometimes I don't see it that way. I recall when my grandfather was in his early 70s and just thought "Wow he's so young" kfkgf, I think the fact that he's always been pretty active helped me see him as younger, despite him obviously being on the older end.