HIIT or High Intensity Interval Training-
Note: HIIT is intended only for advanced trainers. Beginners should stick to the normal 30 minutes cardio workout.
Steps-
1. Strech-Strech your muscles properly specifically the leg muscles.
2. WarmUp- Warmup by doing brisk walkin for a couple of minutes
3. Get Set- Now start running at your normal speed for a period of 6 minutes.
4. Sprint- Now speed the treadmill to the fastest speed you can run.Basically you need to sprint now for a period of 1 minute.
5. Slow down- Now get back to your original speed and keep running for a furthur 5 minutes.
6. Sprint- Repeat step 4.
7. Repeat step 5.
8. CoolDown-Repeat step 2.

This should take you a total of 20-25 minutes.Once you get comfortable with this routine you can reduce the slowdown period and increase the sprint periods.
As this is a high intensity routine, do not do this daily. 2-3 times a week in just fine.