No matter how many miles you've walked, how many diets you've tried, or how long it's been since giving birth, that extra bit of flab on your belly, which arrived along with your baby, doesn't seem to want to budge. Sound familiar? That's why we've gathered these simple ways to reclaim your prepregnancy stomach, once and for all!

The stubborn tummy
(why crunches don't always work)

During pregnancy the outermost abdominal muscles stretch and separate to make room for the expanding uterus. Even after birth, though, when the uterus shrinks back to its original size, these ab muscles can stay separated (after a vaginal delivery or a c-section). And crunches can do more harm than good. "Crunches put pressure on the tissue that connects the outermost abdominal muscles, which can further separate them," says Julie Tupler, a nurse and coauthor of Lose Your Mummy Tummy. The key to toning up your tummy: Brace your stomach and focus on engaging the innermost ab muscle, the transverse abdominus, since this is the muscle that really supports the uterus and gut and keeps your belly sucked in. This also helps prevent back pain.

You can engage and tone your transverse ab muscle while you do almost any activity - or when you're just sitting around. How? Sit up straight, shoulders down, and draw your belly button in toward your spine. "Imagine you're wearing a corset and you're pulling its strings tight," says Lisa Druxman, a fitness trainer and author of Lean Mommy. Believe it or not, sitting this way (say, while you're reading to your child) or standing this way (maybe while you're waiting in line at the store or changing a diaper) will make your abs firmer and flatter. It'll instantly elongate your torso and strengthen your abs and back. If you think you'll forget to do this, tie a piece of string around your waist while your ab muscles are drawn in, and leave it there. Every time you expand your stomach, you'll feel the string pull and remember to keep your abs taut.

Posture perfect

Once you know how to engage your abs (see above), you can turn simple activities into toning exercises. For instance, instead of holding your baby on your side (which causes you to jut out your hip and let your stomach go), hold her in front of you with both arms. "Use your baby as a stabilizer," says Brooke Siler, a Pilates expert and author of Your Ultimate Pilates Body Challenge. Keep your shoulders down and back straight while pulling your belly in toward your spine. "It's hard to hold your baby and that posture for very long, but doing it for even two minutes at a time is a great exercise," she says.