Is it so bad to have a second piece of cake? Or to skip a week of exercising when you feel overwhelmed by work, grandkids and life? The experts say no, as long as you don’t convince yourself it’s always okay.

But if rationalizing that you can be “bad” here and there becomes a pattern, it can sabotage all your stay-well efforts. Heart disease is the nation’s number one killer. To defy denial and keep your ticker on track for the long run, I’ve dissected five common heart health self-deceptions.

Lie #1:  My “bad” cholesterol is high, but I don’t have to worry because my “good” cholesterol is high, too.

Reality Check

“A really high LDL (bad) cholesterol reading can outweigh the benefits of high HDL (good) cholesterol,” said cardiovascular researcher at Baylor University in Houston Christie Mitchell Ballantyne, MD.

LDL cholesterol should be less than 100 and HDL cholesterol should be 60 or higher—preferably in the 80s.

“The further you are from that optimal LDL level, the less likely a high HDL will protect you,” said Ballantyne.

To lower LDL cholesterol, eat lots of vegetables, fruit, whole grains, beans, nonfat dairy and lean protein. One study found that adding plant foods (salad, vegetables, beans) to a low-saturated-fat diet lowered LDL more than simply cutting saturated fat alone.

And don’t cut out all fats. Eliminating unsaturated fats can cause both good and bad cholesterol to drop. Aim to get about 20 to 25 percent of your calories from unsaturated fats like olive and canola oil and less than 5 to 6 percent from saturated fat, which is found in animal products like meat and dairy.

Lie #2:  I don’t have to work out—chasing my grandkids around is enough.

Reality Check

If you spend an hour or so a day running after your grandkids, you are getting some heart health benefits—a modest calorie burn, an immune-system boost, and lower blood pressure and cholesterol levels. But it’s the more intense, sustained movement lasting 30 minutes or more that provides the maximum health and weight-loss benefits.

Transform grandkid duty into exercise. If you typically stroll in the park with a toddler, for example, pick up the pace and try to log in 30 minutes. And while your grandchild naps or plays, strength train at home. Build a workout around push-ups, lunges, walking lunges, squats (sitting in a chair then standing up), calf raises (going up and down on your toes when you’re standing on a stair) and tricep dips. Try to do eight to 12 reps and two sets of each exercise.

You can also use easy at-home equipment such as resistance bands and hand weights.

Lie #3:  I can have two glasses of red wine—research shows it’s heart-healthy.

Reality Check

One drink a day can slightly reduce your chances of heart disease. But make that two glasses daily and your breast cancer risk can rise 25 percent. Your odds of ovarian and esophageal cancer go up as well, according to the National Cancer Institute.

One study found that women who had two to four drinks a day took in nearly 30 percent more calories overall than nondrinkers. Keep tabs on how much you’re pouring: experts consider four ounces equal to one serving, or about one-fourth to one-half of a big goblet.

Lie #4:  I can get by on five hours of sleep a night.

Reality Check:

Skimping on shut-eye is okay every once in a while, but getting fewer than seven hours a night regularly will make you moody, irritable and less productive.

“Sleep debt makes multitasking and the ability to focus more difficult,” said Clete A. Kushida, MD, PhD, director of the Stanford University Center for Human Sleep Research in Palo Alto, California.

The heart health consequences are pretty steep, too. Getting less than seven hours of sleep each night can increase your risk of high blood pressure, which is one of the leading risks for heart disease and stroke. Moreover, being a sleep underachiever can lead to weight gain. People who typically get five hours a night also have 15 percent higher levels of ghrelin—a hormone that can stimulate appetite—than those who get eight hours.

Being overweight or obese can increase your risk of heart disease by increasing blood pressure, LDL cholesterol levels and blood sugar. Excess weight also makes your heart work harder to send blood to all the cells in your body.

To get more sleep, try to go to bed earlier, such as 9:30 p.m. If that’s not possible, try to grab an afternoon nap whenever you can.

Lie #5:  I’m not overweight. I’m just big-boned.

Reality Check:

We know it’s hard to hear, but if your body-mass index (BMI), a measure of fat based on height and weight, is 25 or higher, you may need to lose 5 to 10 percent of your weight, Ballantyne explained. Unfortunately, bone mass can constitute only 4 to 7 percent of your total weight—about 6 to 10 pounds if you weigh 150—and that’s considered too small to affect BMI.

Calculate your BMI at www.bmicalculatorusa.com