People ask me all the time why I do cardio the way I do. I usually answer, "Because I don't have hours and hours to do it every week."

You see cardio is one of those things people just can't seem to get enough of. They come to the gym, and get on to warm up. After half an hour they might do some weights, and abs, and back they go to the cardio. Some people come and just do cardio.

That's because people tell us all the time if you do lots of cardio, then you'll get lean. Fact is that's not how things work.

Just look at the long distance runners in the Olympics, as compaired to the sprinters. The sprinters are leaner and have more muscle. That's because they do short burst work, while a distance runner needs the fat because of the long runs they do. They need the energy.

Now I'm not saying you want to look like a sprinter. But if you want to be lean then start thinking a little more like a sprinter and train to get lean, not to be able to go for a long time.

Do interval training. That's really the key to being lean.

How the heck do you do that? Well there's lots of ways, but my personal favourite is the 45/15 rule. Get on a piece of cardio equipment and start out at the speed you'd go if you wanted to go 20 minutes.

Do this speed for 45 seconds, then sprint as hard as you can for the last 15 seconds of the minute. When that minute is over, drop back down to the first speed again and repeat this for 20 minutes.

If you're outside, use telephone poles to do the same thing. Jog from one pole to the next, and then sprint the next one. Slow to a jog again, and repeat for 20 minutes two to three times a week.

Of course everyone says, "Why only 20 minutes?"

Because if you're doing it right that's all the time you need. If you get back from 20 minutes of interval training and you're not wiped out, you're not working hard enough. Next time speed up.

This type of training with get you into lean, mean shape in no time. Just make sue you eat right while you're doing it.