Losing weight?

alexa
Hi! I'm 17 and I used to be a really active swimmer. My swimming "career" ended with an injury and I haven't been swimming in about a month. I was in really good shape but now I'm starting to gain weight. I don't believe that I am "fat" or "unhealthy" but since losing the body that I once had I am starting to feel very self conscious. Does anyone have any advice to get started on losing the few pounds I've gained?