Most of us rely on our birth certificate to tell us how old we are.
Some rely on a mirror to tell them how old they look.
Unlike cheese and wine, our bodies usually don't get better with age. But that isn't stopping any of us from fighting the effects of Father Time.
With four kids, a husband, a house, and a full-time job, you might think health would come in pretty low on the priority poll for Sheri Snyder.
Snyder says, "To me, health is very important. I think a lot of people take your health for granted, and then something happens and it's kind of too late."
Even though she's careful to squeeze a workout into her workweek and watch what she eats, Snyder still isn't sure she's doing all she can to stay healthy.
She says, "I was a little concerned about cholesterol. That was one number that hadn't been tested in a while, so I was kind of curious where that was going to fall."
When her employer offered a free health screening as part of her health insurance program, Snyder got a good hard look at all her numbers, not just good and bad cholesterol, but also blood pressure, weight, age, even blood sugar.
Snyder says, "We do have a little diabetes on my mom's side, so there's a little concern there."
The number crunching didn't stop there.
Registered Nurse, Lisa Ehrman says, "As we put them into the computer, it ages out their heart and tells them in the next ten years what their risk is for having some sort of coronary event, whether that be a heart attack or a stroke."
Snyder says, "That was a little scary, waiting to see what that was going to show, but reality is what it is."
The reality is her heart is just one year older than her actual age. Not bad, but also not very common.
Ehrman says, "Anytime you tell a 30-year-old man that they have the heart of a 70-year-old, that scares them."
The hope is it scares people enough to make some serious changes in time to reverse the odds in their favor.
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