Unless you've been diagnosed with terminal illness (or one of these 5 deadliest diseases), chances are you don't spend a lot of time thinking about how many days you have left on this planet. While contemplating your mortality might motivate you to live a fulfilling life, it can also be kind of creepy and depressing. So it's understandable that you prefer to push it to the back of your mind.

That said, deep down, you know you aren't going to live forever. How long do you actually have? No one knows for sure, but there are some signs that can help you figure it out. Here are 9 factors that suggest you may be better off preplanning your funeral than saving for retirement (unless you change your ways).

Your parents or grandparents expired early.

Ok, so this one is out of your hands, but your genes are pretty important. How important? "This very question has been looked at in many studies—especially twin studies, where twins had different lifestyles. We now know that for humans, genes have a 25% influence on longevity," says Sharad P. Paul, MD, author of The Genetics of Health: Understand Your Genes for Better Health.

The flip side, of course, is that 75% of factors that control lifespan have nothing to do with your DNA, so you shouldn't assume that you'll live to 100 (or drop dead at 50) just because that's what happened to Grandma. Most experts believe that you have the power to alter the genetic hand you've been dealt, for better or worse.

You don't take your job too seriously.

Workaholics may be doomed by stress, but if you don't work hard or take any pride in what you do you could be in even more trouble. Researchers for the Longevity Project, housed at the University of California, Riverside, found that people who were the most committed to their jobs and who continued to be productive throughout their lives tended to live longer than those who were only in ­it for the paychecks. If you don't want to clock out of life prematurely, find a career that you find meaningful so you'll want to give it your all. (Check out this Prevention Premium story on 25 ways people with highly stressful jobs keep it together.)

You sit all day.

Whether it's in an office or in front of the TV, sitting all day simply is not good for you.  A new study, published in the American Journal of Epidemiology, found that older women who stay seated for 10 or more hours a day have shorter telomeres—protective "caps" on the ends of DNA strands­. The researchers consider this proof that these women have cells that are biologically 8 years older than the women's chronological ages. (So you could be, say, 65, but have the cells of a 73-year-old.) Note to self: Stand up more, and make time for workouts (and add these 6 stretches to your day).

You literally lag behind.

Can't walk as fast as your peers? Unless it's because you recently sprained your ankle, beware. "Slower walking pace—inability to perform brisk exercise—is associated with an increased risk of disability and death," says Paul. Slow gait may indicate that your heart, lungs, circulatory, and/or musculoskeletal systems aren't in great shape. Getting more exercise and seeking treatment for any underlying health conditions (like heart disease) should help get you up to speed.

You struggle to lift a few heavy grocery bags.

You don't have to be able to bench-press your body weight, but lack of adequate muscle mass puts you at risk for a premature death for a few reasons. Weak legs and core up your risk for falls and other injuries that can be life-threatening, and low muscle mass often means you have too much body fat—especially in your abdomen, says Melina Jampolis, MD, a physician nutrition specialist and author of The Doctor on Demand Diet. Abdominal obesity is especially dangerous because it predisposes you to a host of diseases, including diabetes and heart disease.

You don't have a college diploma.

Data from the Centers for Disease Control and Prevention shows that people with a college degree tend to live almost 9 years longer than those who didn't finish high school. Why? Better education likely translates to more knowledge about how to protect your health, plus college grads are more apt to have good jobs that come with access to solid medical care.

Your favorite foods come in a box or wrapper.

If processed junk is your go-to, then it's a safe bet that the quality of your diet is pretty lousy. That makes you more likely to become obese, which raises your risk of heart disease, diabetes, and certain types of cancer, says Jampolis. Healthy eaters—those who score highly on the "Alternative Healthy Eating Index"—have a 25% lower risk of dying early from any cause.

To get high marks based on this Index, you'll need to trade fast food and packaged goodies for lots of produce, whole grains, nuts, legumes, and fatty fish. Moderate alcohol is also considered a good thing. Items to limit drastically include sugar-sweetened drinks, red and processed meats, trans fats, and sodium.

You're divorced or widowed.

This is mostly an issue for the guys, as marriage doesn't seem to be as beneficial to women's health as it is for men's. The University of California, Riverside's Longevity Project found that most men who stayed in long-term marriages lived to at least 70 compared to only one-third of divorced men. So the next time your wife makes a doctor's appointment for you or slaps your hand away from a bowl of chips, remember that the correct response is "Thank you."

You're a smoker.

Duh. We don't really need to explain this one, do we? (The CDC has plenty of specifics if you still need convincing.)

This article originally appeared on Prevention.com.