How do you deal with not being so nervous?

So after MONTHS of searching, doing job interviews, I finally got offered a position. I start to 11/29/2021. And since I got offered the job I've been super NERVOUS. Because I just wanna do a great job, and succeed. Maybe it's because I don't know what to expect, and I overthink ALOT. But I've been thinking about it heavy for the past 2 weeks and even the day before I start. This is only my second job I've had (M)24. Anyways how do you all calm yourself to not be so nervous? I'm trying to stay positive, reassure myself I got this, and keep good vibes because having a positive mental state can help. Thank you so much in advance!

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