I'm 14 and ran a 0.52 for the 400m, what time is acceptable to run at the D1 college level? I have run two half marathons, clocking a time of nearly 1-hour and 50 minutes in both. I am a regular runner and I am capable of running 14 km in under an hour and 2.5 km in under 10 minutes. If I were to get myself prepared for a full marathon, what would be the best method?