We all want to live long lives. We all want to live healthy lives. Health and fitness aren't just an outside interest; health and fitness can play a major role in your success. While the physical benefits clearly matter, the mental benefits of improved health and fitness on your professional and personal life -- perseverance, resilience, determination, and mental toughness -- are just as important.

But being healthy and fit is tough when the nature of most work involves sitting at a desk all day -- and, if you're an entrepreneur knee-deep in launching your startup, all evening, too.

But how can you determine the impact of a relatively sedentary professional lifestyle? Cardiovascular disease and stroke are the leading causes of premature death, making physical fitness assessments a strong predictor of health, but routine physicals don't include sophisticated tools like treadmill tests.

Fortunately, there's a simple, and possibly better, way you can test yourself: Do some pushups.

According to Justin Yang of Harvard's School of Public Health:

Our findings provide evidence that push-up capacity could be an easy, no-cost method to help assess cardiovascular disease risk in almost any setting. Surprisingly, push-up capacity was more strongly associated with cardiovascular disease risk than the results of sub-maximal treadmill tests. [emphasis added]

Researchers studied middle-aged male firefighters (the average participant age was 39) over a 10-year period. At the start of the study, each took a physical, a treadmill stress test, and a push-up test to determine how many pushups they could do in a row, without stopping.

During the next 10 years, 37 cardiovascular-related outcomes were reported, and researchers 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.

Surprisingly, pushup capacity was more strongly associated with reduced cardiovascular disease risk than aerobic capacity, long considered the gold standard of fitness assessments.

Put even more simply: How many pushups you can do might be a better way to evaluate your risk of heart attack or stroke than an assessment of your aerobic fitness.

(Keep in mind only middle-aged, "occupationally active" men were studied; the results may not perfectly apply women or to less active men of other ages.)

How many pushups can you do?

It's easy: Just loosen up, warm 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.

Then evaluate the results:

If you can do 40 or more -- which is really hard -- great!

If you can do only 15 or 20, not so great. But then again, researchers found that every pushup you can do over the baseline of 10 decreases the risk of heart disease.

If you can only do 10 or fewer, you need to get to work. Your risk of heart disease is well over 30 times greater than it is for people who can do 40 or more. (And those are terrible odds.)

Granted, the test isn't perfect. If you're a runner or cyclist, you might bomb the pushup test but by all other criteria be exceptionally fit.

And more important, this is just a simple screening tool that yields indications, not certainties. People who can do 40 pushups today could have a heart attack tomorrow; others who can only do five may live to be 90. Some years ago, I was in extremely good cardiovascular shape and still had a heart attack. Stuff happens.

Caveats notwithstanding, muscle strength, cardiovascular fitness (because by the time you get to 40, I promise you'll be breathing hard), and flexibility make a major difference in overall health, especially as we age.

The pushup test is a simple way to assess those attributes: Not perfect, but certainly 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. And all of those factors indicate a higher risk of mortality.

How many pushups do you want to do?

Improving your pushup capacity is, like most things fitness-related, a simple matter of time and effort: Put in the right kind of effort over a sufficient amount of time and you will improve (which, if you think about it, is incredibly empowering).

Say you can do 10 pushups in a row. Commit to a three-times-a week schedule, one that slowly adds volume to your workout. (And takes less than 10 minutes to complete.)

Week one: Do one set of 10 pushups, rest for 60-90 seconds, do another set to failure (you may not be able to do 10), and repeat one more time for three total sets.

Week two: Do one set of 12 pushups. (Don't worry: You'll be able to do 12.) Then do two more sets to failure.

Week three: Do one set of 14 pushups, and then do three more sets to failure. The goal is to increase your strength and endurance, which is why you add an additional set.

Keep increasing the number of reps per set until you hit 20 in your first set, then add three reps to your first set every week. And add two more total sets to each workout for a total of six.

By week eight, your rate of improvement will have accelerated; you may find yourself doing 30-plus pushups in the first set with relative ease. And by then you'll know how much volume to add to your program to ensure you eventually can do 40 reps in one set.

And you'll enjoy the process -- because improving is always fun. (Trust me: I did 100,000 pushups one year. I know.)

Give the test a try. Ask your friends and family to give it a try.

And If you don't do as well as you like, do something about it. (Here is another great place to start. And so is this.)