It's good for young athletes to take some time off to recover between seasons. Taking time off does should not mean sitting on the couch watching TV. Staying in shape during the winter months can help avoid injury once the next soccer season starts up.
Once you stop playing and training, muscle cells lose most of what they have gained quickly (10 days to two weeks), but the cardiovascular system loses its gains more slowly. Staying in shape during a break requires a mix of frequency, intensity, and duration. Find out how to keep in shape with this great article.