I'm a college freshman, and this summer I was running around 45-55 miles a week, which is about the same I ran last year. I didn't run much more because last year I peaked pretty early in the season (had my best races in late September) and felt overtrained. Last spring and winter I ran 35-45 mpw, about 10 miles more than the year before, with no problem. Now I'm starting to feel overtrained again, even though I'm doing no more than last year, while doing more in the time in between. I feel significantly more tired than I did over the summer (still getting 8-9 hrs of sleep) and my resting HR is now 55-60 (over the summer and before it was always around 45). Does this mean I need to cut back my mileage? I know that seems like the obvious solution, but I'm already running fairly low mileage and barely any workouts (tempos once a week, occasionally fartleks/hills), so is there some other problem?