To perform a weighted side lunge, hold a dumbbell at centermass, standing with your feet shoulder-width apart. Take a wide step to one side, bending the knee of the lunging leg while keeping the other leg straight, lowering your body towards the ground. Push through the heel of the lunging leg to return to the starting position, alternating sides for each repetition to target the quadriceps, hamstrings, adductors, and glutes while also engaging your core for stability.