I'm 29 and i can't talk properly to a girl at work cos she's so attractive

I've just started a new job, and there's a girl that works there who is so attractive that I just can't talk to her properly. I'm not great talking to girls anywyay, but for her it's honestly a real struggle to talk to her like I would anyone else. All my effort goes into maintaining my composure rather than in actually paying attention to her and replying, so that I'm worried I'm coming off as inconsiderate and rude. If I were a teenager I wouldn't worry too much about it, but I'm 29 and I still can't handle being around attractive girls.