Listen to him.  He's pre-med.
Also immediately ditch all the following: 
Heavy weights
iPhone armband with phone while you run = ghey
Calf sleeves 
Fancy clothes that look cool ie the yellow under armor run shirts with a lightning bolt that cost 50 bucks
Gay fitness apps like my fitness pal etc. all you need is garmin connect 
All of the above are useless 
Add the following:
iPod nano or similar small player
Lots of bottles of fluid 
Gel packs 
Shoes that really fit you 
Gps watch 
When stepping up from 5k to halfs nutrition and calories start playing a big role.