Switch Up the Machine
Not just day-to-day, but within a single workout. Three 10-minute cardio routines done back-to-back may be easier for you to mentally digest than one 30-minute bout, and because you will have to work up to your maximum intensity each time you change machines, you will be pushing your body further while conditioning your heart.
Having a program laid out for you in advance can be convenient and motivating, but sometimes the best plan of attack is to not have one at all. Push yourself when you feel like you can (be honest!), and listen to your body for cues as to when to pull back. (Breathing in gasps and trying to ignore that dry-mouth feeling? That's your body telling you to slow down.)
Wheel ’Em and Deal ’Em
Design your own plyo routine with the help of a deck of cards. Choose three different plyo moves before you start (think burpees and jump squats), then deal yourself two cards. Add up the values on the cards (kings, queens and jacks count as 11; an ace is one) and perform that many reps of your first move. When you are done, immediately deal yourself two more cards and apply that number of reps to your next exercise. Continue cycling through your three moves and repeat until the deck is done. Remember to rest when you need it!