Take a gamble on how bad your workout destroys you with the completely unpredictable 'deck of cards workout!'
In order to progress, workouts should constantly be challenging and sometimes even unpredictable. Your body is a clever machine and will adapt to a stimulus faster than Charlie Sheen can say "winning" after doing 3 consecutive lines of coke. Try the deck of cards workout once in a while to really shock the system....
This is the protocol applied to a fat loss/metabolic circuit workout, but it could also apply to a strength or hypertrophy workout too. First off, pick 4 exercises and assign them to a suit. For example:
Spades - battle rope drills
Clubs - kettlebell swing
Hearts - mountain climbers
Diamonds - medicine ball slam
Pick a card at random and add a zero onto the end of the number you get, that's how many seconds you'll perform that exercise for.
For example if I picked a 4 of diamonds that would equate to 40 seconds of medicine ball slams. Rest 60 secs then pick another card at random. It's worth noting I use an ace as 30 seconds and a jack, queen and king as 60 seconds. I also like to put 2 jokers in the pack as well. A joker means 20 seconds on each exercise, no rest in between! Can you see how unpredictable these workouts could get?!