Daily physical activity, even at a mild-to-moderate intensity, can be beneficial, especially if you are currently inactive. The base of the Activity Pyramid is recommending that physical activity be added to your day whenever possible. Examples of these activities are:
Climbing stairs instead of taking an elevator
Parking further away at work or when shopping
Doing yard-work or gardening
Walking the dog
Walking to do errands
Anything which adds extra steps to your day
The U.S. Surgeon General's report, "Physical Activity and Health", issued in 1996 concluded that "activity leading to an increase in daily expenditure of approximately 150 calories per day (about 1000 calories per week) is associated with substantial health benefits."
Many studies suggest you must burn 1500 calories per week to be beneficial for health improvements. Because of this, the Centers for Disease Control and Prevention (CDC) and the American College of Sports Medicine (ACSM) recommend a daily caloric expenditure of 200 calories.
Note there is a difference between physical activity and aerobic exercise. If you are currently inactive your initial goal should be to get moving to gradually increase your energy expenditure toward 150 calories per day. Your secondary goal should then be to incorporate activities of a
intensity while increasing your caloric expenditure toward 1500 per week to reap greater health gains and protection from heart disease and diabetes.