Run more mileage
Do some tempo runs 3 - 5 miles
Run strides
Long run 11 - 13 miles
Mix up the tempos - some, run even pace for whatever distance you decide, others start off at your normal run pace, then pick up the pace every half mile, ideally finishing faster than race pace.
Follw the pattern hard day, easy day, hard day, easy day, hard day.
Dorks who run too fast every day always run "medium" not fast enough to provide any benefit and too slow to recover fully.
Also, I found that if I ran mile/1600m repeats at say 20 - 30 seconds slower than my race pace with a short recovery, then it gave me a lot of confidence and I felt very strong aerboically. Sometimes I couldn't muster a tempo by myself, so I would run cruise miles like I mentioned above - with a 1 - 2 min recovery in between.
The summer between HS and college, I trained just like above - I knew that I had done the right thing when I ran a 5k PR in our opening home fund raising road race - hitting my HS 2 mile PR en route.