I have realised that my boss and someone I work with who is the same grade as me are both about seven years younger than me. I think that is s sign that you don't realise that you are getting older and still believe you are much younger than you actually are.
My grandad used to took about some "old boy" or other that he had seen, but the person was probably 20 years or more younger than him. Admittedly I am considerably younger than my grandad was when he made such comments, but I feel it is a slippery slope. Maybe I don't really want to have an accurate view of getting older though.