Yeah, I'm definitely someone who prefers to spend time by himself. I actually got in trouble for this (sort of) in 7th grade; they made me go to the guidance counselor's office because I was always sitting by myself at lunch. Likewise, when I was in 10th grade and at another school, there was this teacher who would also act as lunchtime monitor, and he didn't like to see me sitting by myself.
But that's just how I am. While some people get an energy boost by being around others, I prefer to just be by myself, listening to music or reading a book. Social situations just don't do it for me.