I am 16 years old, 5'4" & 115 lbs. I have this 5K race in exactly 2 months. I really want to significantly increase my performance. I have a gym membership. Should I do some exercises that work the legs? Should I workout on the treadmill or the 100m track? The race will be on this "hill course". I did the 4K on it last year (20 minutes) and came 45th position out of 120 runners. Unfortunately, I haven't done much cardio exercise for a few months. I often get abdominal cramps. Any workout suggestions will be highly appreciated. I am willing to commit any amount of time needed. Thanks.