I'm worried I may fall into a depression being on disability for a month, how can I prevent this?

Fear can be positive. Your question shows three positives. ! - you're concerned about becoming depressed, 2 - your disability is short term, 3 - you want to prevent depression. That's a real good start to solving the problem. What has made you worry you might get depressed? What is your disability and is it truly short term? Who can you talk to to get answers to those questions? Talk to your dr. Or counselor for help.
Activities. Remain active. Exercise. Maintain social connections with friends and colleagues. Volunteer in something that you enjoy and/or can help your resume. Try a new hobby or restart an old one. All the above are just examples of how to stay active.