I Had a Bad Day

Today I had a bad day. It wasn't a full bad day, just somethings that happened that made me feel upset.
I was at work and as I'm doing my job like I'm suppose to, I realize all of my co-workers are good friends. They all laugh, joke and have fun with each other and I constantly feel left out. I always feel like I don't get along with the like the rest. I'm always the one left out! Literally, always. I hate the feeling. I don't know if it's me or them, but I'm more than positive it's me. I'm always the weird one, no matter where I go.