Exercise does a body good — especially when that body is pregnant. But what happens when your pregnant body is just too tired to get off the sofa, never mind hop on a treadmill?

The fact is, pregnancy fatigue can be a huge struggle for many expectant moms — especially during the first trimester and the last month of pregnancy. And while that physiological reality is a perfectly good reason to take it easier until you're feeling more energetic, it's not such a good reason to write yourself a pass on the gym for the rest of your pregnancy.

Hard as it may be to believe when you're feeling flat-out exhausted, exercise can actually leave you feeling more energized than lying down. Besides being good for you and your baby, working out during pregnancy can even give you back some of that get-up-and-go that you're pretty sure had gotten up and left.

Remember that exercise during pregnancy doesn't have to be exhausting to be effective. In fact, the right kind of pregnancy exercise shouldn't leave you dragging. A prenatal yoga or Pilates class can be even more relaxing than a stint on the sofa. Gentle laps in the pool can be invigorating, especially since swimming allows you to feel spectacularly weightless.

Another tip: When possible, do your exercise outside — the fresh air may give you just enough lift to get going. Keep your energy up by having a light, healthy snack — think protein and complex carbs, like string cheese and a pear — before you strap on your sneaks. And drink plenty of water before, during and after exercise to stay hydrated.

Don't have time to actually take that walk? Build it into your day instead. Walk to the next bus stop instead of catching the one closest to your office, park your car in the farthest spot from the store, or walk to the deli to pick up your lunch instead of ordering in. A 10-minute walk three times a day counts just as much as a 30-minute cardio workout at the gym — even more so if you're more likely to actually do it.

Realistically, there will be days during your pregnancy when even neck rolls and leg lifts feel like too much for your tired body to contemplate. If you can't muster the energy to budge, it's no big deal. Just take advantage of the energetic days — and you will have them! — and remember that exercising regularly may actually bring you more. Really!