I personally don't like talking to random ppl, usually because I have some place to go, trying to study at library, or just like my alone time on the train; not because I hate ppl or something. When people strike up a conversation with me, I am polite, but keep on thinking "when will this be over." When I approach girls I always imagine they are thinking the same thing, and I don't want to be that guy; I can't read them.

What mentality should I have? Or how do I overcome this?