When I had just turned twenty eight I was assumed to be in my mid-40s by someone and my then boyfriend my son (he was six months older) I did not look THAT old, but did make me think about myself and how I looked, which combined with depression, low self image and body dysmorphia I had for at least ten years by then, sent me spiralling downwards for a while.
These days I'm happier in myself, I can actually smile, take the odd selfie, and it shows that I am content in my own skin. People cannot believe I'm almost 42, some assume I'm even late 20s. I was in Sainsburys last year buying cider for a sausage casserole, and the staff member went from chatty to rude in 30 seconds! Assumed I was under 25, couldn't prove I wasn't, and gave me all sorts of crap for looking young! I complained, as shocking customer service, but got told well we do need to check if someone is under 25 (that wasn't my issue their attitude was).