As pp said "old" is someone 20 years ahead of you in the age stakes!
At 68, I honestly don't feel any different to twenty years ago. However, my intolerance levels have risen sky high, and I don't suffer crap as much anymore. I can get away with having a rant these days - "she's getting on a bit, let her be, ha ha".
I'm always given a seat on the bus/tram/train now. The first time that happened was the day I realised L'Oreal Age Perfect wasn't working for me anymore, so I lean into it now and take everything I'm given, Senior reduction, tick, seat on the bus, tick, free travel, tick and so on.
I was out yesterday with my in laws (they're nice) and my brother in law is 92. He is unreal, fabulous skin (unlike mine), no aches, pains, arthritis or any other illness, and he sea swims every second morning at 7 am. I am in awe of him.