Find a sturdy bench, coffee table, wooden box, or kid's chair that allows your knee to be at about a 90-degree angle or larger when you place your foot squarely on it.
Hold a dumbbell or kettlebell in each hand by your side (or, for a more advanced version, in the front rack position at your shoulders).
Step your right foot onto the box, then your left, so both feet are on top of the box.
Softly step the right foot back to the ground, then the left.