Hold a pair of dumbbells next to your shoulders, and stand with your feet shoulder-width apart.
Squat down until the tops of your thighs are parallel to the floor (or as low as you can comfortably go).
As you lower, imagine that you’re screwing your feet into the floor by actively pressing your ankles, lower legs, and thighs outward. (Your feet won’t move, but you’ll be creating tension.)
Push your body up from the squat as you press the dumbbells directly above your shoulders. Your biceps should be by your ears. Lower the weights and repeat.