The answer is more complicated than counting the number of candles you blew out on your last birthday cake. Your daily habits can either add or subtract years from your life—like how much you exercise, or how stressed you allow yourself to be.
Read on for nine things you can start doing today to live a longer, healthier life.
|Drop some pounds|
Being obese increases the risk of diabetes, cancer and heart disease, possibly shaving up to 12 years off your life, per an analysis in the journal Obesity. But being too thin can hike your risk of osteoporosis and poor immune function. So aim to stay at a weight that's healthy for you.
|Cap your drinks|
Regularly exceeding one drink a day or three in one sitting can damage organs, weaken the immune system and increase the risk of some cancers.
|Ease your stress|
Chronic stress makes us feel old—and actually ages us: In a 2012 study, Austrian researchers found that work-related tension harms DNA in our cells, speeding up the shortening of telomeres—which protect the ends of our chromosomes and which may indicate our life expectancy.
Of course, it's impossible to completely obliterate stress.
"What's important is how you manage it," says Thomas Perls, MD, associate professor at Boston University school of Medicine. Practice yoga, pray, meditate, relax in the shower or do whatever else chills you out.
Having more education lengthens your life span, according to a study in the journal Health Affairs, for a number of reasons.
Extra schooling may help you become better informed about how to live a healthy life. And educated folks, as a group, have a higher income, which means greater access to good health care and insurance.
More and more research points to the value of having friends, and not just on Facebook.
An Oxford University study found that being married makes you less likely to die of heart disease, which researchers suggest may be due to partners encouraging the other to seek early medical treatment. Same goes for friendships: Australian research showed that people with the most buddies lived 22 percent longer than those with the smallest circle.
"Having positive, meaningful, intimate relationships is critical to most people's well-being," says Linda Fried, MD, dean of Columbia University's Mailman School of Public Health.
|Extend a hand|
Volunteering is linked to a lower risk of death, a University of Michigan study suggests. But you don't have to log hours at a soup kitchen: Simply helping friends and family—say, by tutoring your niece or assisting your neighbor with her groceries—lowers blood pressure, according to researchers at the University of Tennessee and Johns Hopkins University.
|Work out often|
Exercising regularly—ideally at least three days of cardio and two days of strength training a week—may help slow the aging process, Canadian doctors reported.
"Being physically active is like keeping the car engine tuned," Dr. Fried says. "Even if there's decline with age, it's less severe."
You were never an athlete? Don't worry: Starting to work out now can reduce your likelihood of becoming ill going forward, a 2014 study suggests.
|Reconsider your protein|
A diet rich in processed meat—including hot dogs, sausage, cured bacon and cured deli meats—has been linked to a higher risk of heart disease, diabetes and colon cancer. Limit your intake as much as possible.
|Give up smoking|
Lighting up increases your risk of not only lung cancer but also heart disease and cancer of almost every other organ.
"Just one cigarette a day can take 15 years off your life," Dr. Perls says.
Though you won't instantly revert to pre-smoking health, kicking butts will cut your added cardiovascular risk in half after a year and to that of a nonsmoker after 15.
14 Ways to Age in Reverse originally appeared on Health.com.