I am 16 years old and I recently started running and have set a target of 4 minutes in the 1500m. I have 3 seasons to reach this goal. I currently can run 200m in 24 seconds, but middle distance has never been my strong point. I currently can barely manage 1 mile in 8 minutes. However I am determined to reach my goal of 1500m in 4 minutes and am willing to train as much as possible. What would be the best training plan, considering my current level of fitness and my ultimate goal?