You should not have to much difficulty running a 14-minute mile. If you run at a steady jog you should finish well within fourteen minutes. You could probably take short walk breaks and still be able to do it.
For running a mile within 14 minutes you have to get practise daily and with the help of stopwatch you can monitor daily how fast you are running. You must keep you body fit. By being slim you can run a 14 minute mile. Keep your mind fresh without any disturbance.