That's what I asked. Ok stretch your legs in ways u never done. Ok when you are at a football field get to the beginnings of 5 yards and and then jump as far as you can. Write down where you made it. And do it again the next day. Write down again. Do that everyday. And see how much u increased. Then start running a lot. U will get faster.
Bodyweight is a factor of how fast you can move. Sprinting and exercises that build leg strength are important. Try running with a small 'chute or dragging weight. Not everyone can be a 4.4 or less, but its good to have a goal.