All A/C units falling out of windows aside, sidestepping what's out to get you is actually pretty simple.

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And when it comes to delaying your inevitable demise, lifestyle plays a bigger role than genetics do, per research in the Journal of Internal Medicine. Here are the six biggest threats out there and the best ways to fight them. Plus, if you're already doing them, how you can still up your lease on life.

1. Heart disease
Heart disease is the No. 1 man-killer out there, responsible for one out of four male deaths, according to the Centers of Disease Control and Prevention. While everyone knows exercise can help cut your risk, most men don't realize by how much. Being inactive is as risky as smoking a pack a day, says cardiologist James M. Rippe, M.D., founder of the Rippe Lifestyle Institute and professor of biomedical sciences at the University of Central Florida.

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Already rocking your workouts? Make sure you're hydrating, too. In one American Journal of Epidemiology study, men who drank five glasses of water per day were 54 percent less likely to die from a heart attack than those who drank two or fewer. It may be because water dilutes the blood so it is less likely to clot and make your heart go berserk.

2. Cancer
Following close behind, cancer is responsible for 24.1 percent of all male deaths. And, no, cancer isn't just bad luck. "More than 50 percent of cancers have a significant lifestyle factor," Rippe says. In fact, smoking is the leading cause of cancer death in America, says Aaron Clark, D.O., a family-medicine physician at The Ohio State University Wexner Medical Center.

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Stopped smoking years ago? Try losing some weight, too. Being overweight affects your hormone levels, predisposing you to gastrointestinal and other cancers, Rippe says. Experts believe that within the next 10 years, obesity will replace smoking as the No. 1 cause of cancer deaths in America.

3. Unintentional injuries

Guys seriously need to be more careful. Accidental injuries—like those sustained during car crashes—are the third leading cause of male deaths, per the CDC.

Are you a super-safe driver? You might want to make sure that when you are old and wrinkly, you'll also be a safe walker. Falls take out a lot of old-timers. Start protecting your joints as early as your thirties, says Rippe, who recommends taking a supplement like Osteo Bi-Flex to renew your cartilage and help lubricate joints. Also, most joint problems in men are linked with improperly treated sports injuries, so talk to your doctor about your bad knee, he says.

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4. Chronic Lower Respiratory Diseases 

By and large, this man-killer (it's responsible for 5.4 percent of deaths among men) equates to chronic obstructive pulmonary disease (COPD), Rippe says. Also called emphysema and chronic bronchitis, it strikes the lungs and makes it harder and harder to breathe over the years. Other less common causes of chronic lower respiratory diseases are asthma and pulmonary fibrosis.

Still not smoking? Even if your air's not filled with smoke, it still might be hurting your lungs. Air pollution can significantly up your risk of breathing problems. In one 2013 Bern University study, researchers found that people who lived on or below their building's 8th floor—where air pollution tends to settle—were 40 percent more likely to die from respiratory diseases than those who lived on higher floors.

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5. Stroke

Strokes aren't just your grandpa's problem anymore. Research published in Neurology suggests that up to 15 percent of strokes (which are the fourth-leading cause of male deaths) occur before age 45. The biggest player: high blood pressure, Clark says. If it's over 120/80, talk to your doctor—and cut your sodium intake.

Already cutting sodium-packed processed foods? Drink more milk, Rippe recommends. Milk is the leading source of potassium in the average American's diet, and adequate potassium levels can help combat sodium's negative effects on blood pressure. Bananas and avocados are pretty packed with potassium too.

6. Diabetes

Diabetes is behind 3.1 percent of all male deaths. Meanwhile, 9.3 percent of the U.S. population has diabetes, according to the CDC. But even if you can live with type 2 diabetes, you don't have to. By getting to a healthy weight, you can cut significantly cut your risk.

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Are you at your ideal weight? You still need to get your blood-sugar levels checked every year once you hit 35, Clark says. About 15 to 20 percent of people with type 2 diabetes aren't overweight. Clark recommends getting your blood-sugar levels tested every year after age 35.

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