I lowered my speeds because I can run at 8 mph for approximately 3 seconds, so I changed the first part to be 6.0, 6.5 and 7.0 instead of what's listed. And for the intervals, I did 7.0 and 5.0. It was tough. One of the hardest parts was the uphill climb for 10 minutes. I'm not sure what Level 14 is, but I put my treadmill on its highest incline, which is 12%.