I've been going every few years or so since my early 20s, and even then I noticed the age group of the people in the waiting room, just because it was so different from a GP surgery.
I went a few years ago and the waiting room was full of teenagers, and I felt so ridiculous and out of place. I know it shouldn't matter, but I'm starting to wonder where over 40s actually go for testing. Am I supposed to go somewhere else that I don't know about? I need to go and get something looked at, but I'm already imagining the staff looking at me and wondering what on earth I'm doing there.