CLIFF is a classic interval workout: 40 seconds of work followed by 20 seconds of rest, repeated 8 times. Each round of consists of 4 exercises (SkiErg, Burpees, Rowing, and Wall Balls) that each last 40 seconds followed by 20 seconds of rest. To measure your performance, count your reps per round (1 calorie = 1 rep). The goal is to keep your number of reps as constant as possible for the duration of the entire workout.
Scaling: You can scale CLIFF by decreasing the working times from 40 to 20 seconds.