Perfom each exercise for 1 minute before moving on to the next. Count how many reps you do all up.
Alternating lunges (or jumping lunges if you can)
Alternating side to side prone (on knees OR feet depending on your strength level)
If you do find yourself with more time simply rest for 1 minute and repeat up to three times. Aim to complete the same number of reps (or more) in each ten minute circuit, this will keep you pushing hard throughout.