The point I'm illustrating is that when it comes to building muscle, it pays off to work out your whole body, not just one group.Most guys can rattle off a list of upper-body workouts, but when it comes to what they need to do to build up their legs, they're often at a loss for words.Weight training your legs is actually much easier than you think. Most exercises are just variations of three core workouts: lunges, squats, and the deadlift.Here are three that will give you a strong, toned lower body in no time.1) Lunges.Take a pair of weights in your hands. Stand tall, and then take your right leg and lunge it forward until it forms a 90-degree angle at the knee. At the same time, bend your left leg so that your shins are almost parallel to the floor and there is a 90-degree angle at that knee as well.Hold that position for 1-2 seconds, and then return to the standing position. Repeat the exercise with your left leg. That's one rep. Repeat as often as you like.

Beginner variation: No-weight lunges Same as above, except you don't use weights. You can also increase the angle at which you bend, so you're not bending down as far (this may be helpful if you have knee problems).Advanced variation: Step-up lunges with weights Start in the same position you would for a regular lunge, but place a stool or a stair where your front foot would go. You'll go down like you would for a normal lunge, but you'll place your food on the stool instead of the floor.Lunge forward as far as you can, and then push yourself up on to the stool, using the foot that is already on there as your new standing foot. Step down, and repeat that same pattern with your other foot. Repeat as desired.

2) Squats.Start standing with you feet shoulder-width apart, facing slightly outward. While keeping your back straight, bend at the knees and waist until your thigh is 90 degrees with your calves. Stand back up and repeat.

Beginner variation: Wall squats The most basic version of a wall squat is pushing your back flat against the wall while your thighs and calves are at a 90-degree angles from one another. To do a full on wall squat, you'll start in this position, and then slide yourself up along the wall, keeping your feet in place, until you can't go any higher. Then lower yourself back down until you're at 90 degrees again, and repeat.

dvanced variation: Pistol squats This is basically a one-legged squat. All the same rules apply as above (back straight, thighs should be 90 degrees to calves), but while one leg is bending, the other leg will be held out in front of you.

3) Deadlift. This is one of the most comprehensive muscle-building exercises you can do. It's very similar to a squat in that you start in the same position (feet shoulder-width apart, pointed slightly outward), except this time you'll have a straight barbell with some weights on it in front of you. You'll want the balls of your feet to be under the bar.Bend down like you're doing a regular squat, until you get to that 90-degree point. As you're bent down, grip the bar with one palm facing you and the other turned away from you; they should be spaced slightly more than shoulder-width apart. Then, stand up while you continue to hold the bar... go until you're standing vertically, but with your knees slightly bent.It's important to remember to maintain proper posture throughout all of the movement. Always keep your back straight, and always bend with your knees. Lift the weight with your legs, not with your back. You'll want to keep your abs tight as well to help stabilize your back and the movement itself.It also helps to keep your head up as you're doing the exercise so that you don't lean forward:

Beginner variation: Trap bar deadlift Exactly the same as above, but you're using a special "trap bar" (pictured below), which is more stable than using a typical barbell. You can find a good tutorial on trap bar deadlifting here.

Advanced variation: Wide grip deadlift Again, same movement as the regular deadlift, except your grip will be much wider than your shoulders.

Thoughts, questions, or comments about these exercises or health and nutrition in general?You can post them via Twitter @HealthwireKen, or "Like" our Health Wire Facebook page and post your message on our wall.Yours in health,

Ken Swearengen for Health Wire