Stand on one leg with your knee slightly bent, then begin squats at a brisk pace. Adjust your posture to maintain balance and control. Advanced version: Do the same as the above while standing on your forefoot. Keep moving until your leg is fatigued, then switch sides. If necessary for balance, use a stick, tree, or wall for light support. This will improve muscle responsiveness in the quads, strengthen your knees against injury, and help build stabilizing muscles in your hips.