I'll say it. If it's a lady, the first thing I will think about is whether or not I would sleep with her. If I decide that I do find her attractive, then I begin the narrative in my head where the attractive lady-on-the-train and I begin our life together. I imagine myself walking over there, saying something to her, getting her number, going on a cute romantic-indie-film date in the city, falling in love, making love, having children, sitting on the couch watching Woody Allen movies, hosting a Batman-themed birthday party for our son, arguing in the car on the way to the country-side to visit my parents, etc. It gets really weird and deep, and it all happens in the span of about 3 minutes. I can't even help it.

If they're not an attractive lady for me to get obsessed over, I'll usually just try and build up their back-story based on observation. I'll imagine where they're from, where they are going, why they are going, if they're married or single, if they use a Mac or PC, what their favourite kind of music is, etc. I like watching people to pass the time on the train.

If I find that someone is looking at me, I'll fix my hair, fix my posture, make sure my double-chin or slight man-boobs aren't too obvious, etc.

I don't know if what I'm doing is normal, but I don't think it's uncommon.