Push-ups may be basic, but it takes some time, strength, and awareness to do them correctly. Once you get the hang of this simple exercise, you'll be amazed at how sculpted and strong your arms, chest, core, and shoulders will be. Here are some tips for perfecting your push-up and making it work for you.

Find your form: Before you can move on, make sure you're actually doing a push-up the right way. Be aware of these four things as you execute a push-up: your body alignment, hands, abs, and breath. Make sure your shoulders are aligned over your wrists and your fingers and palms are spread wide, with pressure focused in your fingertips. Pull your belly button in, keeping your spine straight so your body is in a straight line; make sure to connect your breath with your movements. As you lower, bend your elbows outward to the sides. For more information on how to do a push-up correctly, read this guide.

Change it up: Don't stick to boring basic push-ups. While the exercise is great for your upper body, adding props or changing the positions of your hands can make push-ups harder and will work different areas of your body. Add an exercise ball to your feet, for example, to challenge core muscles, and point hands inward to work your triceps more. We've got more ideas — here are 14 push-up variations to try.

More tips for your push-ups after the break.

Happy National Grilled Cheese Day! Just because you're following a healthy diet doesn't mean you have to skip out on this classic sandwich. Check out these tips on how to make a healthier grilled cheese.

• Start with the right bread: For many of us, grilled cheese meant a slice of American cheese melted between squishy white bread. Now that we're all grown up, skip overly processed white bread for a whole-grain variety instead. You'll wind up with more fiber, vitamins, and essential nutrients like magnesium and zinc.
• Not all cheeses are the same: When you're concerned about your weight, cheese can seem like an off-limits food. Although cheese may deliver in fats, it's also a great source of bone-building calcium and protein. When building your sandwich, it's OK to indulge in a full-fat variety, but use a smaller serving — a little goes a long way when it comes to flavorful varieties like Asiago or Parmesan. If you're worried about cholesterol, look for low-fat or reduced-fat varieties, or choose goat cheese. Compared to cow milk cheese, goat milk cheese contains less fat, less cholesterol, and fewer calories. Whatever you do, steer clear of oily, processed American slices.
• Don't stop at cheese: Unless you're a grilled-cheese purist, a sandwich is a great way to sneak fresh veggies into your diet. When making a grilled cheese, consider adding things like red peppers, tomatoes, or arugula. Fruit also works really well when paired with cheese; consider adding some apple or pear slices to your next concoction. Check out this recipe for roasted red pepper, portobello, and smoked gouda grilled cheese.
• Hold the butter: Your sandwich does not need to be slathered in saturated fats, so skip the butter. Instead, try making your grilled cheese on a sandwich press, or lightly spray a sauté pan with your choice of cooking oil.

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Fun issues like nausea, fatigue, shortness of breath, and the need to hit the ladies' room — three different times during a workout! — makes it difficult to keep up with a regular exercise routine when pregnant. If you're expecting, taking up yoga (or continuing to go) is wonderful because not only does it alleviate some of these annoying discomforts, your body will stay strong and flexible. No prenatal yoga class offered in your area? Take a regular class, but be sure to avoid the following during your practice.

• Deep forward bends: Folding forward can compress blood vessels and nerves that connect to your uterus. Keep things flowing by separating your legs like in this Wide-Legged Forward Bend to make space at the top of the thighs.
• Deep twists: This can also decrease circulation, so always twist in an open position as in this pose, not deeply across the knee.
• Lying on your back: Once you hit the second trimester, avoid lying on your back for extended periods of time (as in Savasana). The increased weight of your uterus interferes with the flow of blood and nutrients to your developing baby. It can also aggravate lower back pain, heartburn, and elevate blood pressure. Use blocks and bolsters to prop your torso up instead of lying flat, and whenever possible find ways to stretch the same muscles while you're standing, sitting, on your hands and knees, or when lying on your side.
• Poses that work your abs: As your belly expands, it's difficult to support the weight with your rectus abdominus (the muscles you see when someone has a six-pack), so you use your obliques (ab muscles on the side of your belly). Overly-strong obliques can pull your abdominal muscles apart, causing a condition known as diastasis. Avoid risk by skipping poses that target your core, especially your obliques — worry about getting your abs back in shape after the baby arrives.

Keep reading for more prenatal yoga no-nos.