Heart disease is the leading cause of death in the U.S.—and it seems as if the problem is only getting worse. Nearly half of American adults have some form of cardiovascular disease, according to a new report released by the American Heart Association.

The report, the AHA’s annual Heart Disease and Stroke Statistics update, was published in the journal Circulation on Thursday. For the gigantic report, a panel of experts looked at data from a range of sources (including government reports and clinical trials) to find statistics on cardiovascular disease, which was defined as coronary heart disease, heart failure, stroke, or high blood pressure.

The results showed that 48 percent of American adults (which is about 121.5 million people) have some form of heart disease, and that heart disease is also contributing to an increasing number of deaths. For instance, the report found that that there were 840,678 deaths from the disease in 2016, which is up from 836,546 in 2015.

This reality is something we should all be thinking about, Mariell Jessup, M.D., chief science and medical officer of the American Heart Association, tells SELF. “People need to see that number of 48 percent and realize the odds of an individual having some form of cardiovascular disease is very high,” she says.

Experts say there are a few factors that could be contributing to this trend.

The major issues often come down to lifestyle factors: lack of exercise, smoking, obesity, and not making lifestyle changes when other risk factors for heart disease are present. “The fact that humans have embraced an unhealthy lifestyle contributes to the fact that cardiovascular disease is the scourge of the United States and the rest of the world,” Dr. Jessup says.

That said, people are more active than they’ve been in the past. Adults reported that they’re moving more: In 2016, just 26.9 adults reported being inactive, compared to 40.2 percent in 2005. Unfortunately, they’re still not moving as much as they should. For instance, only 27.1 percent of high school students reported getting at least 60 minutes of daily physical activity, which the authors said in the report is “likely an overestimation of those actually meeting the guidelines.” Federal guidelines recommend that adults get at least 150 minutes of moderate-intensity exercise of 75 minutes of vigorous-intensity aerobic exercise and do muscle strengthening activities at least twice a week—and only 22.5 percent of adults said they’re actually doing that.

Rates of smoking, a habit that’s a known risk factor for heart disease, still have a way to go, too, Helene Glassberg, M.D., an associate professor of clinical cardiovascular medicine at the University of Pennsylvania’s Perelman School of Medicine, tells SELF. While adult smoking rates are dropping—nearly 80 percent of adults said they were nonsmokers between 2015 and 2016, up from 73 percent in 1999 to 2000—there are still plenty of people who are engaging in the habit. That may change in the future, though: Nearly 95 percent of kids between the ages of 12 to 19 were nonsmokers in 2015 to 2016, which is a huge change from 76 percent reported between 1999 and 2000.

Although the link between heart disease and excess weight is incredibly complicated and poorly understood, the AHA consistently names obesity as a major risk factor for cardiovascular issues. And obesity rates may be contributing to the rates of cardiovascular disease, Dr. Glassberg says. Nearly 40 percent of adults and 18.5 percent of kids were classified as obese during the report period, and 7.7 percent of adults and 5.6 percent of children were classified as severely obese.

People also aren’t being proactive about their heart disease risk the way they should. “Many Americans have at least one of the major risk factors that cause heart disease, and many are controllable or at least manageable,” Dr. Glassberg says, citing high blood pressure, high cholesterol, inactivity, being overweight, and smoking among them. “When they’re treated, this significantly lowers the risk of having a heart attack. But many people aren’t doing that.”

If you take high blood pressure out of the equation, 9 percent of American adults (or 24.3 million) qualify for having cardiovascular disease, the report says. However, high blood pressure shouldn’t be discounted: It’s a major risk factor for developing stroke, heart failure, and coronary heart disease, Sanjiv Patel, M.D., a cardiologist at MemorialCare Heart & Vascular Institute at Orange Coast Medical Center in Fountain Valley, Calif., tells SELF. “High blood pressure creeps up on you and many people don’t know they have it until it causes a stroke or heart attack,” he says.

If you’re worried about your own risk for heart disease or high blood pressure, there are a few things you can do.

First off, it’s important to note that the AHA and American College of Cardiology changed the definition of high blood pressure in their hypertension guidelines in 2017 (after much of the data in the report was collected). Previously, people were classified as having hypertension if they had a blood pressure reading of 140/90 or above, but it’s now defined as 130/80 or above. So, if you haven't gotten your blood pressure checked recently, now is the time to do that—even if it hasn't changed much, you might be in a different hypertension category now.

The report points out that about 80 percent of all heart disease can be preventing by controlling high blood pressure, diabetes, and high cholesterol, as well as living a healthy lifestyle. That includes not smoking, eating a healthy diet, being active, and doing your best to keep a healthy weight.

If your job makes it tough to be active during the day, it’s crucial to find time to work out around that, even if it’s going for a brisk walk, Dr. Patel says. “You need to move,” he says. “It can make a big difference in your health.”

It’s also crucial to “know your numbers,” Dr. Glassberg says, which means blood pressure but also cholesterol. “Doing regular cholesterol and blood pressure checks can bring your risk factors to your doctor's attention long before a heart attack happens.”

Getting a general physical exam (where these things are usually monitored) regularly is also important, Dr. Jessup says. (Exact recommendations on how often you should get one vary by age, but MedlinePlus suggests that you see your doctor for a physical every one to two years if you’re between 18 and 39, and every year if you’re over 40.)

If your doctor does find that you have a risk factor for cardiovascular disease, take their advice to follow steps to make a change, whether it’s through lifestyle changes or medication. “The good news is that a significant percentage of cardiovascular disease is totally preventable with lifestyle changes and modern medicine,” Dr. Jessup says