Being hit on is so uncomfortable to me.

I haven’t been an adult for very long and I’ve never really considered myself a very attractive person and I’ve only been hit on a few times before, and I don’t know if it’s just because I’m extremely shy and don’t like flirting with people or whatever, but every single one of those times it just makes me extremely uncomfortable. Is it normal to feel that way? Even though it hasn’t happened to me that many times I just want to know how other people who might be hit on more often feel about it.