Youth will let you get away with less than perfect behavior, assuming that you inherited good genes and your vices are tiny ones. But today is a good time to recognize that tomorrow will take away some of youth’s benefits. Take your strong, healthy heart, for instance. The risk of major problems that lead to heart trouble — high blood pressure, high cholesterol, obesity, diabetes —climb dramatically around the age of 40. Stop these six bad habits now, and you’ll enjoy a healthy heart for years to come.

Smoking

Most smokers who manage to quit meet with failure between seven and 10 times before they succeed. Knowing that failure is a normal part of the process will keep you going, and persistence pays off. Dodging the smoking habit will save you from a major cause of heart disease. Enlist your doctor’s help in making a plan that you can stick with.

Eating the Bad Stuff

Being overweight can lead to heart disease. A better diet will help keep your waistline trim as your metabolism starts slowing around the age of 40. Good eating habits are a good idea at any age, and they grow more important as you grow older. Try to keep your weight within a 15-pound range of the weight your doctor recommends.

“Your metabolism is slowing, so if you’re doing what you’ve always done, you may start gaining weight,” says Dr. Deepak Bhatt. He is the executive director of interventional cardiovascular programs at Brigham and Women’s Hospital Heart and Vascular Center. Dr. Bhatt is also a professor of medicine at Harvard Medical School.

Piling Food on Your Plate

Portion control is important in preventing weight gain that can threaten your heart health. Visualizing portions that are the right size can help you get a handle on potion control. Nutritionists recommend limiting a serving of protein to the size of a fist, grains to a tennis ball and greens to a baseball. Limit butter to a single teaspoon per portion, olive oil to one teaspoon and nut butter to two teaspoons.

Listen to your body when you eat. If you’re still hungry after eating these portions for a normal-sized meal, wait before you dig in again. If you’re still hungry after a short break, switch to low-calories foods such as fruit and vegetables.

Exercising Too Little (or Too Much)

Your heart will grow stronger if you make regular exercise a habit throughout your life. Aim for 30 to 45 minutes a day, three to four days each week. But too much exercise can do damage just as much as too little. Research shows that super-intense workouts such as CrossFit, SoulCycle, or Barry’s Bootcamp may damage the heart, especially later in life. Heavy exercise can also make underlying heart issues worse.

Start recognizing in your 20s that you’ll need a little time to warm up as you grow older. After 40, plan on a 5-minute to 10-minute warm-up and cool down after intense exercise.

Letting Stress Take Over

Stress is a part of life you can’t avoid, but how you respond to stress can make a big difference in your heart health. Lacking control over de-stressing is what can damage your heart in the long run. Look for ways such as meditation to decompress and react to stress in healthier ways.

Retreating from Friends

Research is finding that loneliness and social isolation rank right up there with smoking for putting your heart at risk. One study says cutting yourself off from friends can increase your risk of heart disease by 29 percent. Some experts think that getting together with friends and family may play a major role in reducing stress.

Read More: 6 heart health mistakes you need to stop making before you turn 40