50 Minute, 5.21 Treadmill Routine:

Time Speed
1-2 3.5
2-5 6.0
5-10 6.5
10-12 7.0
12-17 6.5
17-19 7.0
19-24 6.0
24-26 8.0
26-31 6.0
31-33 7.0
33-38 6.5
38-40 7.0
40-45 6.5
45-48 6.0
48-50 3.5
Total: 5.21 miles

Whew – this was challenging! I set the incline to .5% and let me tell you – small incline, big impact!