I always have mine coloured properly before I go on holiday. Inevitably at some time during the holiday there is a "How old are you" conversation.
I always start by saying "I'm 16 and a half" as I was born of 29th Feb, that gets puzzled looks, laugh, then pause as they multiply 16 by 4!
On a recent holiday I was sat next to someone who thought I was younger than her, and she was 56! I just say I've got a good hairdresser and beautician, but mum had lovely skin, even in her 80's. Also, living in a relatively pollution free National Park certainly helps, and I never smoked.
In theory I'd like to stop having it coloured, especially as it grows incredibly quickly. My hair is also ramrod straight so I have it permed as well, have done more or less continuously since I was 16. When it's straight I honestly get depressed, it's so much prettier wavy.