Excuse me, but why are you sitting in front of this monitor instead of getting out in the fresh air and sunshine? I mean, there's like a whole world out there. You don't have to travel to the ends of the earth, either—there's adventure just outside your door.
Many U.S. agencies administer public lands available for recreation: the National Park Service, United States Forest Service, Bureau of Land Management, and Fish and Wildlife Service—search them all at recreation.gov. The nearest to me are Coronado N.F., Ironwood Forest N.M., and Saguaro N.P. Many of these are wilderness areas (some reviewed). At the state level, there are parks in Arizona, New Mexico, Colorado, Utah, and Nevada—check your local listings.
To start you off, a directory of campgrounds by state. Some public campsites can be reserved through Reserve USA/Reserve America (same thing, different interfaces). Pay special attention to Forest Service campgrounds.