If you are struggling to run a 100 metres, then you are unfit. One way to rectify this would be to exercise. There are lots of courses in fitness available but if you can not follow a fitness course on your own, then a wise move would be to use a fitness trainer.
If you don’t need motivating and are very healthy then it is possible to apply for a personal trainer course. By doing this, you will learn how to motivate others into leading a healthy lifestyle.