None of us would build an entire house in a day, and even if we did, we wouldn’t assume the walls were sound. Yet we do that with our health habits, vowing to revamp our diet or start exercising like Lance Armstrong in a day.

The key is making changes that stick: Go gradually. Tackle just one tweak a week, and at the end of 30 days, you’ll be firmly on a new, healthier path. “Building confidence makes change last, and you do that by meeting small goals on the way to the big one,” says Rhonda Britten, author of Change Your Life in 30 Days. “Every time you’re successful, it pushes you to do more.”

What follows are game plans for eating healthy, losing weight, sleeping better and toning up—all in 30 days.

Lose Weight

The math is simple: To lose a pound a week, you need to cut 500 calories a day. Go to CalorieControl.org/CalCalcs.html to find out how many calories you need to stay at your current weight, then subtract 500 from that number. To lose up to 2 pounds a week, step up the exercise as well. As for diet, cutting calories isn’t the only solution—or a long-term one. “You need to figure out what bad habits sabotage your eating and exercise plans and change those,” says Pamela Peeke, MD, author of Body for Life for Women. This month, follow Dr. Peeke’s plan to break four of the biggest bad habits that stop people from losing weight for good.

Week 1: Cut Portions Down to Size
Read the serving size on labels (multiple servings are often included in one package) and learn what a proper portion looks like. A serving of meat, chicken or fish should be the size of a deck of cards; a pancake no larger than a CD ; one serving of cheese about as big as a matchbox; a serving of regular salad dressing should fit in a 1-oz shot glass. For a quickie portion cheat sheet, go to WomansDay.com/Cheat.

Week 2: Have a Healthy Breakfast
Research shows that people who shed the most pounds eat this a.m. meal religiously. Aim to have some lean protein (1 1/2 oz cheese, 2 slices turkey, 2 pieces turkey bacon), a little “good” fat (1 Tbsp olive or canola oil), and good carbs (whole grains like oatmeal or whole-wheat bread). Try an egg white omelet stuffed with veggies and 1 1/2 oz lowfat cheese, or 1 cup lowfat yogurt with 1/3 cup granola.

Week 3: Stop Eating After Dinner
After the kids are tucked away and the house is quiet, we’re tempted to reward ourselves with food. Instead of undoing your diet, reward yourself another way. Pick up the phone and have a chat with a friend, play Scrabble with your husband, or take a long, soothing bath. If you really need a treat, have a low-calorie one (no more than 200 calories) like a Skinny Cow ice cream bar.

Week 4: Curb Afternoon Cravings
Late afternoon—from about 3 p.m. until 5—is when you’re most likely to need an energy pickup. You’ll end up grabbing whatever’s easiest, so be prepared. Save half your lunch and have it now (half a turkey wrap, a small portion of grilled chicken on greens). That way, you won’t be ravenous by dinnertime.

Tone Up

“Building your exercise program gradually helps prevent aching muscles and injuries,” says Wayne Westcott, PhD, author of 24 fitness books, including Get Stronger, Feel Younger. Westcott’s plan uses just a few exercises to firm your legs, abs and upper body. Go to WomansDay.com/Toned for a video of these moves.

Week 1: Power Up Your Heart
If you’re a newbie to exercise, start with 10 to 15 minutes on a stationary bike two to three times this week. If you’re already active, do cardio three days a week, 30 minutes a day.

Week 2: Strengthen Your Core
A strong core is central to just about everything: good posture, preventing back pain, flat abs. Start with the trunk curl. Lie on your back with knees bent, feet flat on the floor, hands resting behind your head. Lift from your abs, focusing on lifting your upper body toward the ceiling. Do 2 or 3 sets of 12 to 15 reps twice a week. Also add 5 to 10 minutes to your cardio, making it a little harder by walking faster or using a higher resistance on the bike.

Week 3: Tone Your Arms and Upper Body
Do an upward row: Stand holding a 3-lb dumbbell in each hand, palms facing the fronts of your thighs. Bend your elbows as you slowly lift your arms up until the dumbbells are just below your chin. Lower back down. Do 2 to 3 sets of 12 to 15 reps twice a week. Add intervals to your cardio by alternating a fast pace with your regular pace for 3 to 5 minutes. Add this variation on the trunk curl to your core workout: Instead of lifting straight up, bring the left elbow to the right knee, come back down, then lift up, bringing the right elbow to the left knee. Do 10.

Week 4: Round Out Your Routine
The hip dip works your chest, shoulders and triceps. Sit on the edge of a sturdy chair, hands gripping chair next to hips. Lift your butt and walk forward, keeping hands on chair and back straight, until your butt is hovering just in front of the chair. Lower hips until elbows are bent at right angles, then come back up (don’t sit). Do 2 sets of 12 to 15 reps. Advance your core work with the classic bicycle: Lie on the floor, hands behind your head, knees bent, feet off the floor; crunch up, bringing each elbow toward the opposite knee. Do 2 sets of 12 to 15 reps. Congratulations! You’ve built a short, effective workout. From now on, do 20 to 40 minutes of cardio three times a week and all of these moves together (about 15 minutes) twice a week.

Eat Healthy

“Eating well is about continually making good small choices,” says Wendy Bazilian, DrPH, RD, coauthor of The SuperFoodsRx Diet, who created this plan.

Week 1: Add a Fruit, Add a Veggie
Work your way up to eating a fruit or vegetable at every meal (for at least 5 servings a day). Start by adding blueberries to your cereal and having a side salad with lunch. Fruits and veggies fill you up for minimal calories and have disease-fighting nutrients. Generally, the more vivid the color, the more nutrient-dense they are.

Week 2: Pump Up the Flavor
Try a new herb or spice at every meal—you’ll need less salt, sugar and fat. Herbs and spices are concentrated sources of antioxidants, too. One tsp of cinnamon has the antioxidants of 1 cup of pomegranate juice; 1/2 tsp of oregano has as much as 3 cups of spinach. Sprinkle cinnamon in oatmeal or coffee grounds. Put paprika on potatoes, fresh basil in sandwiches.

Week 3: Switch to Lowfat Dairy
Lowfat milk (nonfat is best, but some people prefer 1% or 2%) has nine essential nutrients— including calcium, vitamin D and phosphorus for stronger bones—plus protein. Nonfat or lowfat yogurt contains “good” bacteria that helps with digestion and boosts immunity. Aim for three servings a day (one serving equals 1 cup yogurt or milk, 1 to 1 1/2 oz cheese).

Week 4: Eat for Energy
That means eating every three to five hours, which amounts to three meals plus two snacks. Be sure to have a combo of protein and carbs—a balance that keeps your metabolism stoked (so you’ll burn more calories) and your appetite in check. The right snacks have a small amount of fat and 150 to 200 calories. Prep them in advance so they’re “grab-’n’-go” ready.

Sleep Better

“Getting good sleep boosts your energy, your mood and your concentration,” says Mary Susan Esther, MD, president of the American Academy of Sleep Medicine.

Week 1: Set a Sleep/Wake Routine
To fall asleep fast (and stay that way), turn in and wake up at roughly the same time every day—even on weekends. This will help your body naturally start to wind down around the time you go to sleep. Also make sure you get plenty of light exposure first thing in the morning: Open the blinds right away or have a cup of coffee on your porch or in your backyard if you can. It reinforces the sleep/wake rhythm that you’re trying to establish.

Week 2: Create Calm
Your bedroom should be a quiet, peaceful place. Watch TV somewhere else in the evening (and try to avoid the news right before going to sleep; it can make you anxious), and move all things digital (computer, cell phone, BlackBerry) far away from your bed. Make sure the room is dark; even little light sources like a digital clock or cable box can keep you awake. Set the thermostat at 68°F or open windows. Research shows that people sleep better in a cool room.

Week 3: Say No to Stimulants
And we don’t just mean caffeine—which you should avoid after noon even if you don’t think it affects your sleep. (Remember, chocolate and some sodas also contain caffeine.) Working in front of a computer screen— no matter how small—is also stimulating, so log off about an hour before bed. And try to avoid alcohol about two hours before turning in. As your body metabolizes it (which takes a few hours), you can pop awake.

Week 4: Make Time to Relax
Worry is a big sleep saboteur, so set aside “worry time” earlier in the day to take stock of what you need to do, even write it down. If you can’t nod off in 15 minutes, get up and read a book or magazine and head back to bed when you feel sleepy. This teaches your brain that bed is a place to fall asleep. One note: If you have sleep troubles nightly for several weeks, talk to your doctor. He can screen you for any medical conditions that might be the cause.