Here are a few ways to mix up the workout:
1. Perform the exercises in reverse order.
2. Mix up the reps (do higher reps first and decline to lower reps)
3. Pick a “magic” number for the session and have the client perform all exercise to that “magic” number.
4. Perform the complete set of exercises and add a brief bout of cardio after each round or in the middle of each round. (Can be cardio machine based or cardio type moves)
5. You can incorporate Tabata Training (20 seconds of work and 10 seconds recovery, 8x, will roughly take 4 min. per exercise)
6. Perform a time-based circuit rather than counting reps.
7. You can also add in a piece of equipment such as BOSU or stability ball which will change the intensity of the circuit.