For Americans, the average life expectancy now surpasses 78 years, an increase of more than 4 years since 1980. Unfortunately, the incidence of chronic disease is increasing as well, particularly among those who are not yet elderly. In other words, more of us are experiencing poor health earlier in the aging process and living with it longer.

A new study published in the Archives of Internal Medicine suggests that we can improve our chances of healthy aging by being fit in middle age, regardless of whether we had previously exercised. This study compared the results of an aerobic fitness test administered by the Cooper Institute to more than 18,000 healthy men and women, average age of 49, and then compared the results against Medicare claim records when the same individuals were in their 70s and 80s.

They found that those who'd been least fit in middle age were the most likely to have developed serious chronic diseases (including heart disease, diabetes, Alzheimer's and colon or lung cancer) at an earlier age. Those who had been fit at the initial assessment often developed the same diseases but significantly later in life, typically for the final five years of life, instead of the final 10 to 20 years.

It's never too late to begin exercising, and the earlier you start, the longer you'll benefit. To move out of the least fit category, aim for accumulating 30 minutes of moderate intensity aerobic activity most days of the week. Just three 10-minute or two 15-minute walks a day can dramatically improve your chances for a healthy old age.

For Women's History Month, let's acknowledge the women who've made a difference in our lives!

I know a woman who never fails to inspire, and she happens to be my mother. Irene is the kind of woman that people gravitate to because she is always interested, kind, non-judgmental and grateful. She has a can-do spirit and yet is patient while awaiting results. "Something will happen," she said to me recently, "It always does."

Just shy of her 95th birthday now, I asked Irene what has allowed her to reach this advanced age. Off the top of her head, she gave me these principles to live by:

• Observing the rules of health, taking my medications
• Continuing my interests, like reading (she has a Kindle!)
• Moderation, especially in foods
• By all means, exercising

Mom and I are not sure if she inspired me to a career in fitness or if I inspired her to love exercise! Although she spends most of her time in a wheel chair, Irene continues to do strength training for her standing and walking ability. She works with a trainer in the fitness center twice a week, doing 15 minutes on the seated stepper with arms and the weight machines for upper and lower body strength.

Irene is living proof that there are no excuses! What woman has made a difference in your life?

Here's a bold example of the life-changing power of exercise! I first met Dr. Alvin Jones a year ago when he interviewed me on his radio show about my book Strength Training for Women. Afterwards, he asked for my help in a weight loss program, and to date, he has lost 73 pounds. (Scroll back to see more posts about Dr. Alvin).

Alvin was 56 when we met over the air waves and began our "virtual relationship" by e-mail and phone. He recently told me that this past year has been "the first year of my life, of being an adult, of maturing. I look better, feel better and it's been the best year of my life."

The program I gave him is so elementary that anyone can do it, no fancy equipment or gym memberships required! You just need your body and commitment to your goals. Consistency and dedication are key. The formula is basic but well-established: daily exercise combined with better food choices equals dramatic benefits for your health, appearance and state of mind.

Beyond weight loss, the positive lifestyle approach has caused a "paradigm shift" for Alvin. Taking care of his body has improved his mental discipline, which extends to other areas of his life. The skill set he learned from our program - consistency, accountability, perseverance – is the baseline for high performance and the foundation for doing something great.

Coming of age can happen anytime in life!

Push-ups, sit-ups and squats - timeless bodyweight exercises - provide a mini full-body workout that you can do anywhere, anytime, with no equipment needed. But are you making common mistakes in form that can sabotage your efforts?

Join us live on Sirius XM's Dr. Radio Show this Wednesday, February 20 from 8-9 am. I'll share all the insider tips that I've learned over the past 25 years as a fitness professional and answer questions such as:

• What are the biggest mistakes that people make in performing each exercise?
• Why is spinal alignment the key to getting the most out of these moves?
• How can you work these exercises into your lifestyle, no matter what your fitness level?
• What is the difference between a sit-up and a crunch?

Call in with your questions and comments to 877-NYU-DOCS

Vivacious host Dr. Marina Kurian sets a lively tone in her show and engages her audience with humor and personal insight. I'm always delighted to appear with her! Catch us live this week:

LISTEN LIVE: Dr. Radio Show
DATE: Wednesday, February 20
TIME: 8:00-9:00 am ET
LOCATION: Sirius XM Radio Channel.81
Call in with questions/comments: 877-NYU-DOCS

We all do it, every day. Some of us do it for most of each day. We do it at home, at school, at work, at ball games and at the movies.
What is this pervasive risk factor that can cause early death? It's called "sitting" and Americans average 9.3 hours a day compared to 7.7 hours of sleeping.

The dangers of too much sitting have been making recent headlines:

• Extended sitting slows the body's metabolism reducing levels of fat burning enzymes and HDL cholesterol.
• Sitting too long raises your risk of type 2 diabetes, heart, kidney and liver disease, and certain kinds of cancers, even for people who meet the recommended physical activity levels.
• Sitting more than 6 hours a day increases your risk of death, even if you work out.
• Watching TV for 6 hours a day robs 5 years off your life.

Being sedentary for the average 9 hours a day is killing us! So what to do if you can't quit your day job? And if exercise won't help anyway, what can Americans do to truly combat the negative effects of sitting for long?

• Set a daily schedule and periodically, at least once an hour, take a 2-minute break of light to moderate activity. Walk around your office, climb some stairs.
• Make exercise a part of your meetings: Switch your coffee meetings to walking meetings. Block off time in your calendar.
• Stand at the back of the room during company meetings or ask your company to create a collaborative meeting space at standing height.
• Develop an "active work station" such as a standing desk or a treadmill desk.
• Instead of hitting the vending machine at 3 pm, make a point to stand up, stretch and do a few leg exercises like squats and calf raises.

A small, simple change can have a dramatic impact on your health. Even if it seems elementary, the consistency of doing a "little bit a lot" is a formula for success.

Are you more afraid of getting cancer than heart disease? If so, you're not alone. According to the American Heart Association, while it’s true that heart disease is the No. 1 killer in women, only 1 in 5 American women believe that it is her greatest health threat. The best defense against heart disease is a hearty offense, and from the physical activity standpoint, that means cardio exercise and strength training.

Cardio (or Aerobic) Exercise: Regular cardio exercise can lower your blood pressure, improve your cholesterol levels, reduce body fat and enhance circulation. Cardiovascular stamina is associated with a stronger heart muscle, slower heart rate, decreased chance of heart attack, and a greater chance of surviving if you do suffer a heart attack.

Lifting Weights: The heart is a muscle that gets stronger and more efficient with training, pumping more blood with each beat. Strength training, like cardio exercise, can improve the function of the heart and lungs and provide additional benefits such as:

• Enhance glucose metabolism
• Reduce your risk for diabetes
• Aid in weight control
• Ease the demand on the heart in response to physical or emotional stress

Why would you want another medication when instead you can take this "magic pill" – truly magic because the only side effects are totally beneficial! Click here to see more about my easy-to-use books on strength training.