You don't need anyone to tell you that exercising during pregnancy does a body good. But you also don't need anyone to tell you that a pregnant body is a tired body — especially in the third trimester.

It's not surprising that when you engage in exercise in the third trimester, your body messages you to get off the treadmill and onto the couch. After all, who deserves to put up those feet more than you do?

But before you get too settled on that sofa, consider this: The right kind of prenatal exercise can actually give you back a bit of the get-up-and-go that you were sure had pretty much gotten up and went. That, in turn, can provide you with a much-needed physical and mental health boost.

But that doesn't mean you need to plop yourself onto the treadmill. A 10-minute walk three times a day counts just as much as a solid 30-minutes on the elliptical.

Still sound like too much? Push yourself to sneak a little extra walking into your day: Walk to the next bus stop instead of catching the one closest to your home, set a timer and take a short stroll around your office every hour, park your car in the farthest spot from the store, or walk to the deli to pick up your lunch instead of ordering in.

Skip high-impact workouts, which can feel uncomfortable and potentially strain your joints. A kinder, gentler form of exercise in the third trimester: A prenatal yoga class, which needn't be strenuous and can be more relaxing than lying around. Plus it gives you a chance to practice the breathing techniques you'll soon need.

A few slow, easy laps in a pool can also be invigorating — plus, swimming while pregnant takes some pressure off your swollen ankles for a little while and reminds you what it's like to feel weightless. 

As long as it's not too hot, exercise outside. The fresh air may give you enough lift to get you going. And don't forget to grab a light snack — think protein and complex carbs, like hard cheese and whole wheat crackers — and some water before you lace up your sneakers.

And while feeling sluggish is one thing, if you feel dizzy, are short on breath, or develop a headache or chest pains, it's time to throw in the towel (and, in the case of the latter, give your doctor a call).

Realistically, there will be plenty of days during the final weeks of your pregnancy when even shoulder stretches and neck rolls feel like too much hard work for your weary body — and that's no big deal. Just take advantage of the energetic days, keeping in mind that even a little exercise in the third trimester just may bring you more of them.