I did it!
My patented treadmill fartlek. 60 minutes divided into 10 minute increments - 2 minutes at 7mph, 2 at 8 mph, 2 at 9 mph, and 4 at 10 mph. Actually worked up to 5:50 pace for the last couple minutes.
I tried to do this last week and failed.
I'm also down to 147 pounds. Down about 10 pounds from December.