With his long red and gray beard, pale skin and clear blue eyes, Aubrey de Grey, 48, looks like a Harry Potter character, a saint or a visionary. His vision is indeed rare:  de Grey sees a time when we’ll live in peak health for a thousand years or more. If his calculations are correct, the first marathon-running 150-year old hottie may be…your big-eyed toddler.One hundred and fifty could be the “new 40” or 25, and perhaps you could even look as good as you feel.Predictions like these are a staple of science fiction, and when de Grey first offered his ideas several years ago, prominent scientists publically dismissed them as “pseudo-science.” But there was a difference this time around: When a top journal offered a $20,000 reward to any molecular biologist who showed that de Grey’s analysis was “unworthy of learned debate,” no one won.The author of “Ending Aging: The Rejuvenation Breakthroughs That Could Reverse Human Aging in Our Lifetime,” de Grey stresses that he’s interested in health, not mere survival. The goal is new preventive medicine. About 19 percent of people who reach the age of a hundred today are “escapers,” as scientists put it—they haven’t developed the major illnesses of aging.   The rest are enduring with a chronic condition: about half suffer from dementia and arthritis and nearly three-quarters have heart trouble.  That’s exactly what de Grey doesn’t want to see. The very old are much happier when they’re healthy or when they perceive themselves to be healthy, according to some research, not to mention common sense. I didn’t envy the centenarian who said to me on the telephone recently, “I’m tired. I can’t do the things I used to do . I’ve lived too long.”QUIZ: Are You Living Your Healthiest Life?She can look to her genes for those extra years. Compared to their peers at earlier dates, the old-old didn’t eat less or exercise more, according to a large study reported this year by the Albert Einstein College of Medicine of Yeshiva University.  In one sign of genes-based longevity, many centenarians have children in their late 40s, says Jay Olshansky, co-author of “The Quest for Immortality: Science at the Frontiers of Aging.” Such extended fertility may allow sex hormones to provide greater anti-aging benefits. Sakhan Dosova, who died in 2009 soon after her 130th birthday, had claimed she gave birth at 54. (130? Believers point to a Soviet-era passport and Kazakhstan identity card recording her birthdate as March 27, 1879).Since old-old age is a genetic lottery, until de Grey’s rejuvenation breakthroughs arrive, most of us don’t need to worry about passing the century mark. But it’s still up to us to keep our bodies running as well as possible to ensure that a long life is a blessing, not a curse. That means eating healthily, maintaining a healthy weight, and getting sufficient sleep and exercise. Diet, for example, is linked to everything from mood to arthritis, and obesity has been linked to shorter lifespan due to the diseases it is associated with. (One study suggested that it can shorten lifespan by an entire decade.) Rather than counting calories, focus on long-term habits, a “live-it” (over a “die-it”) that includes breakfast and filling up with good oils, whole grains, nuts, and fruit and vegetables.COLUMN: All Foods Aren’t Created Equal, by Dr. Oz and Dr. RoizenYou also need to enjoy your life to look and feel good—and vice versa. Happy elders are inspiring for everyone, maintaining active days, interests and social ties. Interestingly enough, artists and performers are especially peppy, suggests a new study from Columbia University.  Analyzing professional performers ages 62-97 in Los Angeles and New York, the study begins with this quote from a 93-year old actor: “I’m like an old whore. I can do the work; I just can’t do the stairs.” As a group, the performers were unusually satisfied with their lives and healthy, and independent but not isolated: while they tend to live alone, they typically work 20 hours a week and communicate daily or weekly with other artists.Dorothy Custer, who turned 100 in June, expressed her personal motivation when she told the National Centenarian Awareness Project: “I just love the sound of applause.” Custer, who appeared on the “The Tonight Show with Jay Leno,” around her birthday, performs thirteen characters, making her own costumes. Jazz trumpeter Leonard “Rosie” Ross celebrated his 101st birthday in 2007 at his “home away from home,” the Pine Cone Inn, in Prescott, Arizona, where he’s had a Friday night gig for decades. When asked how he’s lived so long, he credits his trumpet. “I love to entertain and make people happy. I look forward to each gig. And that makes me happy. As long as people want to hear Harry James ‘You Made Me Love You’ or Clyde McCoy’s ‘Sugar Blues,’ I’ll be here to play it for them!” A similar sense of purpose and engagement with your work can extend your life, no matter your profession.Love can help us stay healthy, and live longer: The aptly named Dorothy Young, an actress and painter who performed with Houdini, showed up at 101 for a Barbara Walters special in 2008 with her then-94 year old boyfriend. “Dorothy told me that she is happier now than she has ever been,” Walters wrote in her book, “Audition.” “She had found true love. So there you are.  It really is never too late.”Companionship need not be romantic to boost your wellbeing. Centenarian identical twins  Eloise Rogers and Lois Fisher see each other every day; male centenarian identical twins, Curtis and Curran Carter, live a mile apart. “With us, togetherness would be the word,” Curtis said to the Evansville Courier & Press.” Before one of us thought of something and it was gone, the other had the same thought.”Participating in group activities is characteristic of contented elders. Mardy Rawls, at 84, shows her watercolors in galleries and regularly travels to France with a group of painters. She plays tennis often and helps organize a neighborhood group that enables older people to stay in their homes. Gail Winslow, who maintains a full workweek as a financial advisor in Washington, D.C. at 81, plays tournament duplicate bridge four times weekly and tennis five times a week.“It’s a total cliché. You’re only as young as you think you are,” says Pat Herson, 84. ”I am fascinated with people. Everybody has a story to tell you. It’s often uplifting, exciting. I make a point of trying to talk to people to as many people as I can.” Herson has traveled to nearly fifty countries over her lifetime, often bringing her guitar and singing with local people.  At home, she frequently hikes with friends in Sequoia National Park, in California.Religious belief is a longevity-boost. A variety of studies show that elderly women live longer when they attend services and pray privately. My grandmother, who lived independently until 92, kept the Sabbath and attended synagogue every Saturday, kept kosher, observed all fast days, and prayed at home. I never asked her the secret of her energy—I didn’t need to.QUIZ: How Healthy is Your Body?For those seeking to add years with extraordinary health measures, Dr. Oz recommends hyperbaric oxygen therapy (only when done in the safety of a hospital), which keeps stem cells healthier. Sports stars and celebrities have been getting oxygen therapy for years. Eating about 30-40 percent fewer calories than normal or less than 2,000 calories a day—depending on your height and build—can turn on a body process called the “sirtuin” chemical pathway, which is associated with famine and makes your body conserve resources. Some believe it can extend your lifespan as well, though severely restricting calorie intake is a controversial practice. To capture the same results, Sirtris Pharmacueticals of Boston and other companies are investing in trials of sirtuin-related drugs .While scientists look for the secret of youth, you can do your part to prevent wrinkles, of course, by taking care of your skin, staying out of the sun or wearing sunblock, maintaining a healthy BMI, and not smoking. One study found that facial-cream users looked about two-and-a-half years younger. Higher levels of estrogen can also keep skin elastic and prevent thinning.  Avoiding sugar may help, too.Winslow keeps a pitcher of water on her desk and reminds herself to leave her chair and walk around. “When you’re 81, you’re not gorgeous,” she says. “I get up every morning and look in the mirror and all I can say is, ‘Thank god for another day.” If de Grey’s predictions are correct, we may be rising to many more mornings than we could ever imagine.