How to make an office more cozy?

I finally got a job with an office! I'm super psyched to have my own little room and I feel like such a grownup because of it! Yay!
I've been unemployed for months now so I don't have any money to do any proper decorating. The office is a small dark room on the first floor and it has boring grey walls. The only stuff in the room are a desk, a chair and a computer. So the office definitely needs some decorating to make it enjoyable to spend a lot of my time in there.
So, what kind of stuff do you have in your offices? The cheaper, the better! Suggestions about free stuff are also apperciated :)
I'll start at my job in a week and I'm so excited!


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