Stand with your feet hip-distance apart, holding a dumbbell at each shoulder.
Slowly bend your knees as if you were going to sit in a chair, keeping all the weight in your heels. Don't let your knees move beyond your toes, and don't let the knees roll out or in. Squat down as low as you can, keeping your head and chest lifted, your spine long, and your shoulders relaxed.
Press through your heels, and slowly straighten your legs to stand up. Make sure to keep your spine neutral. Do not round your back.
Do three sets of 15 reps.
Trainer tip: use 15-pound dumbbells. If that's too heavy or too light, change the weight.