I'm a heterosexual guy, so I think I wouldn't care to time travel to any age and examine myself. It just wouldn't get me off, as interesting and unique this question is. And that's because looking at me doesn't arouse me.
Instead, I'd time travel to the exact moment I developed a fetish for girls in masks within the medfet context (my main fetish and one I post about a lot on here). First anesthesia masks (I *think* this moment was when I received a children's book about what the surgical experience might be like, and saw a pic of a girl my age who had a "black beauty" mask held on her mouth and nose as she lay down on the OR table), and then protective masks, which is 90% of my mask fetish now.
Who was the girl I was first turned on by because of her wearing a protective mask on her mouth and nose? What did she look like? What were the circumstances? Was it an earloop mask? Tie-on? Cone? Elastomeric half mask (EHMR)? How did *she* feel wearing the mask, especially since, before COVID, mask-wearing was largely hidden?
ETA: As I write this, I figure maybe there is a relevant exam. Maybe a fit testing after thepatient is informed that, due to her low immune system, she will have to wear a mask in public. I have no clue if that's true, but if so, it would be fun to be a fly on the wall during the fit test.
ETA 2:
Being turned on by medical exams isn't shameful, it's a great fetish! Take up any opportunity for examination or comparison!
Well said, and to my younger self, I'd say:
"At this age, you don't understand sexuality, but masks are a turn on for you. Never be ashamed. Explore this fetish when possible, in every way that you want to and can. Do not suppress yourself. There is a concrete and sensical root to this particular fetish for you, and in this instance, it may make the hospital less traumatic going forth. "