Based on the 2008 Physical Activity Guidelines for Americans
By the U.S. Department of Health and Human Services

The guide booklet provides tips on assessing what level the person is at and
how to get started; incorporating physical activity into their life;
maintaining the exercise habit and goals to keep throughout life for ages 18
to 64 years.

The webpage to see each part of the guide is here:
http://www.health.gov/paguidelines/adultguide/default.aspx#toc

or you can use this link:
http://www.health.gov/paguidelines/pdf/adultguide.pdf