I run 3-4 times per week, totalling 20-30 miles per week, at mostly at a fairly easy pace of 7:30 - 8 minutes per mile. I am 35 years old hobby runner, have been running for 3 years and my current PBs 1500/4:30, 5k/17:45, 10k/36:50, HM/1:28. Some people tell me to increase my mileage to get better but when I try to do so, I feel tired, my calves and feet hurt and I tend to develop little pains so I am forced to reduce my mileage back for fear of injuries. Maybe my body is just not build for higher mileage. Since I started running I shed almost 20 pounds, my upper body got very lean but running had no effect on my legs as I still have pretty thick calves and thighs and now I am 6'1" and 175 lbs. Do I definetely need to increase my mileage to get better at 10k and halfmarathon? What if I may not profit from the higher mileage and should speed up in training instead. Is there anybody from you with sub 35minute 10k or sub 1:20 halfmarathon (e. g. my ultimate goals) and 30 miles per week or less?