I would like to believe I am years away from my peak mileage so please keep that in mind, but want to go about training intelligently, hopefully to be running strong years from now too..before 2 years ago I never ran farther than 60 minutes..I ran a 74 minute 10 miler this past February and have a 19:38 5k time..chances I break 1:40 in the HM on a hilly course? I am putting in regular 20-25 mpw, and one week I hit 28 miles recently.