How to gain confidence in myself?

So the past month maybe, I realized I am like very anxious and not very confident in social situations. Like I realized this at my new job I started working at. Like the people there don't make me anxious or nervous or anything. It's just that they're new people and i had no idea who they were, what they were interested in, etc. But I started to like a girl at my job and I literally can't talk to her. Which is weird considering at my old job, I could talk to any girl that walked in and out with no problem. But here talking to anyone or specifically girls is almost impossible. My goal by at least Christmas time is to become more confident in myself with my looks, my personality, etc and just feel better and know myself better. What ways do you know of that could help me?

How to gain confidence in myself?
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