Stand with your feet shoulder-width apart; keep your arms at your sides or in front of your chest, as shown.
Step forward with your right leg and lunge, lowering your hips until both knees are bent at about a 90-degree angle. Keep your back straight (no leaning, hunching, or rounding your shoulders).
Return to the starting position and perform the same movement on the opposite leg.
To make the exercises more challenging, do it with a kettlebell, a set of dumbbells, or a weighted plate.