Liz Neporent is a diet and fitness expert and author of 12 fitness bestsellers. She regularly appears on national TV programs and is the president of Wellness 360, a New-York based wellness provider.

It's so frustrating when you make an effort to lose weight -- an honest-to-goodness, try-your-heart-out effort -- and it goes nowhere. (Of course, who doesn't feel a smidge of impatience right from the get-go? There's always a little part of you that expects to be transformed after just one workout.) My clients often cite lack of results as one of the top reasons for giving up on an exercise. So, for those who have ever felt like they've been left at the starting gate when trying to lose weight by exercising, here are a few tips that may help.

Work Harder. When you first begin an exercise program, even a leisurely stroll can leave you sucking wind. After a few weeks, you'll notice that the same amount of exercise won't leave you quite as breathless, and your heart won't thump quite as loudly. That's a sure sign of progress, but it's also a sure sign you need to kick into a higher gear. In fact, there's some scientific evidence to suggest that doing one or two hard-hitting workout sessions a week can rev up weight loss; when you push yourself, you burn a greater number of calories per hour and can pump up your resting calorie burn rate for several hours -- or even several days -- afterwards. For stalled weight-loss efforts, add one to two weekly "interval training" workouts (that's where you mix speedy, high-intensity intervals lasting one to five minutes with slower recovery intervals lasting an equal amount of time).