Intervals..on a treadmill (ha! just fixed a typo- orginally I had typed "internals..on a treadmill..nice visual!!)

6x 2min intervals at 6% grade. (2min rest in between) then
2x2min @5%
2x2min@6%
2x2min@7%
10 min Zone 2 (160)
CD

ouch!!