Satchel Paige was around 60 when he took the mound for the last time in 1965, throwing three shutout innings for the Kansas City Athletics.

Clearly this super-star of the Negro League and the majors embodied one of his favorite sayings: "Age is a question of mind over matter. If you don't mind, it doesn't matter."

But a new study reveals that for many of you, the middle years are a time of decline, not achievement, at least when it comes to health.

A Duke University-led team enrolled 775 participants of both genders and many races/ethnicities, ages 30 to 100, and had them go through the paces: repeatedly rising from a chair for 30 seconds; standing on one leg for a minute; and walking for six minutes.

Regardless of gender or other demographics, physical decline started showing up in the 50-year-olds.

That means as you reach your 50s, you need to increase physical activity so you protect or increase agility, balance, speed and strength.

That'll help protect you from a precipitous decline that accompanies being overweight, inactive and inflexible - diabetes, immobility, obesity, heart disease and a roster of chronic problems from digestive woes to cancer.

So, today's the day (at any age!) to start walking 10,000 steps daily; doing strength-building two to three days a week; jumping (you'll get higher over time) 20 times, twice a day; and practicing yoga for balance and flexibility.

Then your next 50 years may be filled with as many (or more) interesting adventures as your first 50!