Did you know that muscle building starts with your legs? Some of the largest muscles in your body are in your legs and, as a result, working them out will affect your overall strength and fitness. That's why it's wise to focus on squats and dead lifts. These two exercises pinpoint the quads and hamstrings but when you're performing the lifts, a lot of other muscles in your body are tensing. So, focusing on your legs will provide you with a double benefit: your quads will have a more defined look while the rest of your body gains from the holistic effects of the lift [source: Mehdi].