I'm in high school right now and just about to begin my XC racing season. I've been running Monday-Friday with my team and doing about a 10 mile long run on Saturday for a total of roughly 50 miles. On Sundays I've been swimming at a pool, doing 30-40 minutes of laps, and sometimes mixing in some harder intervals. Note that I'm a completely awful swimmer, and only know freestyle, so I don't go but so fast, but at the same time I think swimming benefits me more because I'm so awful at it I have to work really hard when I do it. Ive gotten better at swimming, and my ling capacity in the water has definitely improved, as on my first day i had to come up 3 times to breathe to swim a lap, and now i can do one without breathibg. However, I'm worried I'm wasting my time. Is this a good regimen, or should I instead rest on Sunday, or do a short/easy run, or some other kind of cross training? Any advice would be appreciated, thanks.