Your lats will like this.

The latissimus dorsi is the biggest muscle in your back. Actually, you have two of them—one on each side of your spine, just below your shoulder blades. Lats are bigger muscles, which means they burn a decent amount of calories when in use so it pays to make them work. And it pays to make them work hard because toned lats foster a bulge-free back. Many people turn to chin-ups, but those can be difficult if you're at a lower fitness level. Lat-specific machines and cable/overhead bar setups all work nicely, however they often make you sit down. There's nothing wrong with sitting, but I'm of the mindset that more of a challenge can be achieved when you stay on your feet. Why? Because you have to call on the lower-body muscles for support.

When I work my lats, I use a cable crossover machine like the one shown at left. (Thanks, Google Images!) And actually, this particular machine is set up exactly how you'd want it to be in order to perform the following:

To begin, grab one handle in each hand and center yourself between the two. (We want even lats, right?) Step back about a foot so that your arms are now slightly in front of your body. You may be leaning forward slightly so bend at the knees and hips to create a comfortable squat.

Maintain this position as you pull your elbows down to your sides, keeping your palms facing forward the entire time. Really focus on depressing those shoulder blades to help engage your lats. Control the weights as you straighten your arms again. Repeat as desired, but always take a breather in between sets. As you progress, try standing on a BOSU to further challenge that lower body. Trust me—it's so fun!