This article has some surprising facts. The biggest one is that in spite of many people knowing that exercise is good for your health, only 20 percent of American adults over the age of 18 meet the government’s recommended guidelines when it comes to physical activity.

The average adult needs at least two hours and 30 minutes of activity each week, if it’s at a moderate intensity level, like brisk walking. Up the intensity to jogging or running, and you can aim for at least 75 minutes a week. Add in a couple of strengthening sessions a week, and you can expect to build muscle, protect your heart, avoid obesity and even live longer.

Consider a few profound factoids: Regular exercisers have a 40 percent lower risk of developing dementia, and a 60 percent lower risk of any type of cognitive impairment, according to a 2012 study. In young adults, regular exercise can increase bone mineral density by as much as 2 to 8 percent a year, according to the New York Times, helping to prevent dangerous falls and fractures later in life.

But it takes some discipline, adherence to routine or commitment to exercise even this little. Also the time away from work and personal obligations. As someone who couldn’t make the time for decades–or didn’t care to–I really understand. Now I can’t imagine a week without around an hour of exercise plus 5-10 hours of tennis. Who would have guessed? I definitely feel better for it and know that it is keeping me feeling more energetic, enthusiastic and vital.