Five Ways to Live Longer

The average American is expected to live to 78.

But we can take steps to boost our longevity.

On "The Early Show", Men's Health magazine Senior Associate Editor Joel Weber showed us how we can add years to our lives.

He says it appears we're succeeding at living longer, stronger and happier lives: Centenarians (people who hit 100) are one of the most rapidly growing segments of the U.S. population, according to the National Institute on Aging. The number of centenarians is growing at a rate of 4.1 percent per year; the numbers increased 51 percent between 1990 and 2000.

The five keys to sticking around longer:

Eat Your Vegetables, and Raw

Italian researchers have found that eating as little as one cup of raw vegetables daily can add two years to your life. Why raw? Cooking can deplete up to 30 percent of the antioxidants in vegetables. That said, sautéing, steaming, or blanching them is far better than not eating them at all. If you consume more than five servings of fruits and vegetables per day, you have a 26 percent lower risk of stroke than people who eat fewer than three servings, according to one British study. Try to eat as many different colors of vegetables as you can, and keep in mind that darker greens tend to contain the most vitamins and nutrients. Spinach, Swiss chard, kale, and collard greens are all excellent choices. When making salads, experiment with flavorful greens that you're not too familiar with -- watercress, for instance, which has a peppery kick. A study from the American Journal of Clinical Nutrition found that eating three ounces of watercress every day increases levels of the cancer-fighting antioxidants lutein and betacarotene by 100 and 33 percent, respectively. Just go easy on the salad dressings, which tend to be high in calories and sodium. For a healthy, easy-to-make DIY dressing, mix two parts extra-virgin olive oil with one part balsamic vinegar, and then add salt and pepper to taste.

Crack Some Shells

When Loma Linda University researchers tracked the lifestyle habits of 34,000 Seventh-Day Adventists -- a population famous for its longevity -- they discovered that those who munched nuts five days a week earned an extra 2.9 years on the planet. Not surprisingly, nuts are one of the healthiest snacks you can have. High in monounsaturated fats and protein, they help keep your arteries clean and your stomach feeling full. Eat two handfuls a day as snacks betweens meals. Almonds are especially good for their high doses of vitamin E and magnesium, but walnuts are a good alternative because they contain more heart-healthy omega-3s and pack half as much protein as chicken. Or you can opt for Planters NUT-rition Heart Healthy Mix, which contains six key nuts, including almonds and walnuts. Just remember to always opt for raw, unsalted nuts. Smoking and salting increases the sodium content, which can have a negative impact on your blood pressure. Be especially wary of macadamia nuts. Though a great source of monounsaturated fats, they're often covered in salt.

Check Your Belly

The fat you carry today could kill you tomorrow. University of Alabama researchers discovered that maintaining a body-mass index of 25 to 35 can shorten your life by up to three years. BMI is a simple calculation of a person's weight-to-height ratio that doctors often use to determine a person's health risk. According to the National Institute of Health, a BMI of 19-24.9 is normal, 25-29.9 is overweight, and 30 or greater is obese. Excess body fat raises your risk of diabetes, heart disease, stroke, and colon cancer and, unfortunately, the bad news doesn't even end there. As a man's waist size goes up, his testosterone goes down. In one landmark 2007 study, men with a 5-point increase in BMI -- about 30 extra pounds on a 5'10" guy -- had testosterone levels comparable to men who were a full decade older. Women need to watch their BMI, too. A study published in the International Journal of Obesity found that nearly a third of young women with a normal BMI still carry excessive body fat. Research also suggests that gaining more than 20 pounds from age 18 to midlife doubles the risk of post-menopausal breast cancer. Calculate your BMI using an online calculator. To improve your score, try circuit training-a conditioning technique that combines the best aspects of strength training and cardio into a single activity by having you move from one weightlifting station to the next without rest. Then persuade your significant other to join. A Duke University study showed that sedentary people are 50 percent more likely to work out three times a week if their partners participate.

Invite Your Friends Over

Chronic stress weakens the immune system and ages cells more quickly -- ultimately shortening life-spans -- but friendships can act as a buffer against stresses of everyday life. When Australian researchers looked at seventy-somethings, for instance, they found that those with the largest network of friends had the longest lease on life. For the average person, this could add up to seven additional years. But acquaintances aren't friends: You need people you can openly confide in. In a survey conducted jointly by Duke University and the University of Arizona, sociologists learned that women today report having an average of only two close confidants, down from three in 1985; nearly a quarter of the women surveyed reported having no one at all in whom they could confide. So say "hello" to the neighbor you've never met, invite your closest friends over for game night, and then maintain rituals, whether it's a simple weekly Sunday night phone call or a yearly stay in a beach villa.

Find a Happy Place

In a Yale University study of older adults, people with a positive outlook on the aging process lived more than seven years longer than those who felt doomed to deteriorating mental and physical health. If you're outlook has some room for improvement, give back to your community by volunteering or mentoring-selfless actions that distract from unhealthy obsessing, according to studies. In addition to helping others, don't forget to care for yourself. Make yourself happy by doing the activities you enjoy most-whether it's going to the spa for a facial, drinking green tea (which is loaded with antioxidants in the evening), or hitting the links. Golf even has a life-extending effect, according to a Scandinavian study, because it engages people in a stress-reducing social activity, gets them outside for several hours, and makes them walk the equivalent of four miles.