Second to unintentional injuries (resolve to not be a jackass in 2013, guys), heart disease is the leading killer of men under 40, according to the CDC. “One of the biggest risk factors is untreated high blood pressure,” Dahmer says. “About one in three adults suffer from high blood pressure, and of those, one in five don't know it,” he adds. Ignoring it could lead to strokes, heart attacks, kidney and eye problems and heart failure. The magic numbers to hit are 120/80. If you're teetering on 130/80 or higher, talk to your doctor about ways you can improve your odds (for example, cutting back on salt, saturated fats, and alcohol) without taking meds.