Step forward with the right leg hitting noon, come back to center, take that same leg to about 1 or 2 'o clock, and then go back to center. Step out to 3, then 4 or 5, and then finally six.
Think big giant steps. If you step short, your knee will take the weight and it doesn't want it. Do as many as you can slowly and evenly for 60 seconds.
If you want to work harder, grab a few heavy cans or jars and lunge. And harder yet, raise your arms over your head while doing your lunges, and of course, make sure and do the lunges on both sides.
But if by chance you have knee issues, try the move squatting directly out to the side of you, then directly behind you, which will take the pressure off your knee but still allow you to work the entire leg while revving up your metabolism.