I am 15 and today I ran a continuous, Tempo, 14km (8.7miles) in 59:40 (4:16 per km/6:26 per mile) on a flat course. At the end I felt like I could have kept running for a few more km's if I had to.
I did this about one week back into training after a 2 week break with injury.
What I want to know is, what could I run for a half that I have in about 4 weeks? Is sub 90 minutes an achievable goal?