John has contributed a letter to a book called Dear Me: Letter to my 16 Year Old Self in which celebs write letters to their 16 year old selves.
I got the book today and have scanned the entry below - it's short and sweet but quite funny.
I'd definitely recommend the book. Its a really nice little hard back and only £5.99 on Amazon at the moment with a £1 going to Elton John's AIDS Foundation and its got some really sweet letters in - especially the one written by Stephen Fry.