There are many possible circuit training ideas. I’m going to list some just off the top of my head.
– Pick three exercises. Do each one for a minute before moving onto the next with no rest. Repeat this all for five rounds.
– Pick a strength exercises that you can only do for one to five reps. Have a conditioning move you can do a hundred reps in. Go back and forth between the strength exercise and conditioning exercise for a number of rounds. (This builds the ability to apply maximal strength while fatigued. Great for fighters.)
– Have 10-20 exercises of varying difficulties. Do as many reps of each before moving onto the next. Keep track of the reps for each exercise and your total time.
– Have an implement like a kettlebell on one end of a field. Do a set number of swings with it. Sprint to the other side of the field. Do a bodyweight exercise like pushups. Run back and repeat.
– Pick a number of exercises to work the whole body. Do a set followed by jumping rope for a minute. Go onto the next exercise then jump rope for a minute. Continue in this pattern stopping after you’ve done each exercise or just going once through them all.
There you have five potential workouts. With variations of each you could use these for the rest of your life.
Personally I like to mix it up with my circuits. Plan something then go after it. As long as you keep track of your workouts you can do something similar a month down the road and see how you’ve improved.
Alternatively, you can add a few reps or a bit of time to each exercise thus making each circuit harder. Do this on a regular basic and you have a formula for improvement.
P.S. As for calve work as David mentioned about his Convict Conditioning Routine I haven’t directly worked my calves in even distant memory. Sprinting and/or jumping rope is all you need.