Martha Graham, who danced and taught for more than 70 years, knew a thing or two about vitality. "There is a vitality, a life force, an energy, a quickening, that is translated through you into action, and ... this expression is unique," she said. 

Unfortunately, a survey of 10,000 U.S. adults reveals that only 18% have "high vitality," meaning they are healthier, exercise more often, are less likely to be obese, and more likely to have a primary care doctor than others.

Among the other benefits they gain, it turns out that regular exercise increases the effectiveness of the COVID-19 vaccines.

A study in the British Journal of Sports Medicine shows that the COVID-19 vaccine is effective for keeping people who exercise regularly out of the hospital 85% of the time, while vaccinated folks who get little or no exercise only gain 60% protection.

Theories about how that works include:

• Moderate physical activity helps antibodies and white blood cells detect and fight illnesses earlier than they might otherwise. 

• Exercise helps lower stress hormone levels, and lower stress may protect you from illness.

• Physical activity clears "bugs" out of the lungs and airways, and your rise in temperature during and right after exercise may prevent infectors from growing.

You can increase your vitality and improve your vital signs and your vaccine's effectiveness with 10,000 steps a day, cardio three days a week at 80% of your age-adjusted maximum (a heart rate of 220 minus your calendar age is your max), and strength training twice a week.