Move closer to school
On the practical side I would say determination is another factor that helps.
Give yourself a target time and try as hard as you can to make it. Remember to believe you can do it.
When you are angry or scared it is amazing how much power you have. Being determined to reach goals is one way to trick your mind and body into beeing slightly stronger than normal. Another trick you could use is if your girlfriend phones you and says she's beeing assaulted at the top of the hill, I bet you could do it within 90% of your current best time
(but I won't recommend this)