I have a hard time going out when I can just crash and lay around in my dorm room where I live by myself. When I live with other people I never do that as I don't like being stuck in the same room with someone all day so it forces me out to go do things. But now that I have my own room I have a hard time going out, not really being forced to go out so how can I break this bad habit of crashing all day doing nothing?
Get rid of things like games consoles or tv in your room so you wont have as much to do inside. Then you will want to go out more :)
Your college should have some services available to you nearby such as a sports centre and restaurants and clubs. Go out to bars and other social gatherings, involve yourself with strangers. If this seems too much at once, just go down the corridor and knock on a neighbor's door. Explain that you just wanted to know who lived next door to you and ask their name and so on. Getting to know people and making friends is really the first step. From what you have said, you make it sound like you are pretty lonely. Don't forget you are there to study but a healthy social life contributes to the whole student life and experience.
Paint the walls and leave while it's drying so you don't get sick.