38 Minute, 4 mile Treadmill Routine:

Time Speed Incline
0-2 4.0 1%
2-5 6.5 1%
5-8 7.0 1%
8-10 7.5 1%
10-11 8.0 1%
11-29 Repeat minutes 5-11 three more times 1%
29-32 4.0 1%
32-38 4.0 4%
Total: 4 miles

That’s 3 minutes running at a comfortable rate, 2 minutes where you’re slightly uncomfortable, then 1 minute at an all out sprint!