Are there any college or university half backs that can give me advice?

-how to increase my 40 yard speed


-good upper body workout


-good size for a halfback(i am currently 5'4 190 pounds)


please tell me what i need to work on i want to be an exceptional running back. I JUST NEED SOME GOOD TIPS. Also what can i do during the winterAre there any college or university half backs that can give me advice?
Im not a college running back but I do play a little half back in high school and from little experience I have I think halfback isnt your position I think you should be playing cornerback