Practice makes perfect! Well just make sure you take walks and strengthen your leg muscles and drink lots of water:) an if you don't wanna take walks alone grab a friend or even a dog. They have leashes that you wrap around your waist so the dog can run and you can basically chase it.
Parachute drills. Get a small parachute hook it to your back to create wind drag. Sprint short distances daily for a good stretch of time. Then when removed you should see a difference. It does work. It builds leg muscle and strengthens your core. Used in pro sports all the time.
What I do is run a mile everyday and time my speed. I run even faster the next time, it helps keep your speed at a great distance. I play soccer also and our coach makes use do many different sets of sprints and i have brought up my speed with in the first 2 weeks.