CRUSH A HILL CLIMB!
Start at a rate of perceived exertion (RPE) of 6 to 7 on a scale of 1 (very light effort) to 10 (the hardest you can go). Sustain that effort for about 10 minutes. Then push harder (RPE 7 to 8); hold it there for about 8 minutes. Finish by notching it up to an RPE of 8 to 9 for the final 2 minutes of the interval. Do two of these efforts for 20 minutes each, with 10 minutes recovery in between.