WASHINGTON — Sworn in as the 21st secretary of defense on Jan. 20, 2001, Donald Rumsfeld (search) has had a career that has taken him from the cockpit of a Navy fighter plane to the top spot at the Pentagon (search). In between, Rumsfeld has made successful pit stops in Congress and at the White House.

He said he rarely gets burned out, except on the really long diplomatic missions.

"The only time I ever really feel it is if I go a long period without exercise," Rumsfeld said. "The other risk factor for me is relaxing. Once you relax, you wind down and then it's hard to get cranked back up again."

In a week that marks the one-year anniversary of the war in Iraq (search), Rumsfeld, considered one of the most intriguing figures in Washington, D.C., gave Fox News unprecedented access to view him in action throughout his daily schedule.