tSuccess rarely happens overnight -- especially in business, where success is almost always the result of years of sustained effort.

It takes time to make the right connections. It takes time to build a great team. It takes time to create long-term, loyal customers

In business, longevity matters, so much so that Warren Buffett calls time "the Methuselah technique": the financial advantages of a long life and a high rate of return.

And then there's this: Research shows a 60-year-old startup founder is three times as likely to found a successful startup as a 30-year-old startup founder, and is 1.7 times as likely to found a startup that winds up in the top 0.1 percent of all companies.

In short, the longer -- and healthier -- you live, the more likely you are to be successful.

But how can you know if you're at greater risk of dying sooner? Here are a few simple tests.

Just keep in mind that each test yields indications, not certainties. "Passing" any of the following doesn't guarantee lower mortality risk. Shoot, I was in extremely good cardiovascular shape and still had the dreaded widowmaker heart attack. (Although I could argue that my outcome could have been a lot worse had I not been in great shape, so there is that.) 

Even so, each test involves some degree of causality, not just correlation.

Plus, research shows that achieving a high score -- or working to improve your scores -- can help you perform better under stress. Can elevate your mood for up to 12 hours. Can increase the production of a protein that supports the function, growth, and survival of brain cells. Exercise can even improve attention, concentration, and learning and memory functions.

So yeah, there's that too.

And with all that said, here we go:

The Pushup Test

Researchers had participants take a physical, and do a treadmill stress test and push-up test. Over the next 10 years, they determined that men able to do 40 or more pushups during the baseline exam were 96 percent less likely to experience a cardiovascular event than those who could do only 10 or fewer.

(For some reason they only studied men. Sigh. Since Army standards say women perform 40 to 60 percent fewer pushups than men, we'll split the difference and use 50 percent fewer for women in the results below.)

Even though aerobic capacity has long been considered the gold standard of fitness assessments, pushup capacity was more strongly associated with reduced cardiovascular disease risk.

Give it a shot. All you have to do is warm up, loosen up, and then do as many pushups as you can. If you have to stop and rest, you're done. If you put a knee down, you're done. Just crank out as many solid pushups as you can:

  • If you're a man and can do 40, or if you're a woman, 16 to 20, that's awesome (That also makes you an outlier.)
  • If you're a man and can do 15 or 20, or 8 or 10 if you're a woman, not as great. Then again, researchers found that every pushup you can do over the baseline of 10, or 5, decreases your risk of heart disease.
  • If you can do only 10, or 5, or fewer, your risk of heart disease is over 30 times greater than it is for people who can do 40 or 20 or more. (Eek.)

Sure, the test isn't perfect. For example, serious runners or cyclists might bomb the pushup test but be exceptionally fit by most other criteria. Or you may have a shoulder problem that makes doing pushups problematic.

But still: muscle strength, cardiovascular fitness (because the more pushups you do, the harder you'll breathe), and flexibility make a major impact on overall health, especially as you age, and the pushup test is a simple way to assess those attributes. 

It's not perfect, but it's at least directionally accurate. If you're overweight, the test is harder. If you lack flexibility, the test is harder. If you're in poor overall physical condition, the test is harder. Research shows each of those factors indicate a higher risk of mortality.

Want to be able to do more pushups? Here's a straightforward program that will yield fairly quick results.

The Walking Test

A University of Sydney study found that people who can walk at a fast pace (3 to 4 miles per hour) have a 24 percent lower risk of all-cause mortality compared with those who walk at a slow pace. For those 60 or over, the effect is more pronounced. People who can walk fast enjoy a 53 percent reduction in all-cause mortality.

As the researchers write, "These analyses suggest that increasing walking pace may be a straightforward way for people to improve heart health and risk for premature mortality."

Map a one-mile course, or crank up your fitness tracker, and walk as briskly as you can for a mile. Then evaluate the results.

And keep in mind there's an added bonus. Another study shows there's a definite link between physical fitness and improved cognitive function that results in improved memory, reasoning, sharpness, and judgment. 

Want to increase your walking speed? Here's a straightforward approach.

The Sitting-Rising Test

A study published in European Journal of Preventive Cardiology found that how well you can go from a standing, to sitting, to standing position indicates whether you're at greater risk of mortality.

Here's how it works. Stand barefoot on a non-slick floor with plenty of open space around you. Cross one leg over the other, and lower yourself to a sitting position. Then try to stand back up. (Here's a video showing how.) 

The goal is to do it without touching the floor with your hands, knees, elbows, forearms, or the sides of your legs. 

Now score yourself. Start with 10 points, and subtract half a point for each time you needed to use your hand, or knee, or forearm, or shift onto the side of one leg before levering yourself up. Also subtract half a point if you lost balance.

The bad news? People who scored less than 8 points were two times as likely to die within the following six years compared to those who scored higher. People who scored 3 or less points were more than five times as likely to die within the same period compared to people who scored more than 8 points.

But there's also good news. Managing to increase your SRT score was associated with a 21 percent decrease in mortality. If you scored a 6 today, and next month you score a 7, your mortality rate decreases significantly.

That's because flexibility, balance, and muscle strength make a major difference in overall health, especially as you age, and the SRT test is a reasonable indication of overall activity and fitness levels: If you lack flexibility, the test is harder. If you lack balance, the test is harder. If you're overweight, the test is harder. All of those things may indicate a higher risk of mortality.

Want to improve your results on the sitting-rising test? Here's a great place to start.

The Grip Strength Test

A 2018 study found handgrip strength works as a proxy for measuring overall body strength and muscle mass. 

More to the point, handgrip strength is "strongly associated with a wide range of adverse health outcomes. Lower grip strength correlated with higher incidence of cardiovascular disease, chronic obstructive pulmonary disease and various types of cancer."

One way to test your handgrip strength is to use a dynamometer. (They look like this.) If you have one, here's a chart.

But since most people don't have a dynamometer, another way to evaluate grip strength is to hang from a pull-up bar for as long as you can. Simply loosen up, take a few deep breaths, and start hanging.

For men, consider 60 seconds a good target. For women, 30. But in some ways the initial target is irrelevant. The researchers found that a 6-pound decrease in grip strength for women, and 11 pounds for men, correlates with a 16 percent higher risk of dying from any cause.

Do a little math and that means if you're a woman and can only hang for 20 seconds, or a man who can do only 30, your mortality risk is likely higher.

On the flip side, improving your grip strength should correlate with greater longevity, since grip strength is an accurate bio-marker in that it reflects the overall condition of your skeletal muscles. 

Want to improve your grip strength? Squeeze-y trainers are relatively inexpensive. Or you could just hang from a pull-up bar every other day. (And mix in a few pull-ups while you're at it.) Your strength will naturally increase. And if you get bored with that, start doing one-armed hangs. You'll be surprised by how quickly you'll improve.

And that's the best part of all. Working to improve one thing -- how many pushups you can do, how fast you can walk, etc. -- naturally leads to doing other things. 

Many people, once they start to work out regularly, naturally begin to eat healthier. One study found that people who exercised for 12 weeks (long enough to make exercise a part of their lifestyle) still liked fatty or high-calorie foods just as much, but no longer wanted to eat them as much.

As the researchers write, "Exercise might improve food reward and eating behavior traits linked to the susceptibility to over-consume."

Or in simple terms, I still love ice cream, but a by-product of exercising regularly -- of wanting to improve one area of my life -- means I don't crave ice cream as much.

That's the beauty of the improvement ripple effect. Working to improve one thing, and sticking with it, naturally leads to improving other things -- often without having to make a conscious decision. 

Or needing willpower to overcome your resistance to change.

And that's a definite win-win.