The Democrat said she is too much of a free spirit to be tied to a desk job.
During a stop in Fresno on Tuesday to promote a tax program for low-income Californians, Shriver said she is focused for now on her latest projects, a best-selling book and an HBO special about Alzheimer's disease. She did not expressly rule out a campaign for public office in the future, however.
"I'm not really comfortable in the office. I'm too much of a free spirit," she said in an interview with The Associated Press. "I'm trying to use my entire life experience from being in a public family, my experience as a reporter, and everything else in the work I'm doing right now."
Shriver, a member of the Kennedy political dynasty, said she is not ready to endorse any of the candidates exploring campaigns to replace her husband, Republican Gov. Arnold Schwarzenegger, who will be termed out of office in January 2011.
The potential Democratic field already is getting crowded, with former governor and current Attorney General Jerry Brown, San Francisco Mayor Gavin Newsom, Los Angeles Mayor Antonio Villaraigosa and Lt. Gov. John Garamendi among the better-known politicians considering a run.
Former eBay chief executive Meg Whitman, Insurance Commissioner Steve Poizner and former Rep. Tom Campbell are vying for the GOP gubernatorial nomination.
The seat of U.S. Sen. Barbara Boxer also is up next year, but the Democrat is seeking re-election.
Shriver, a former NBC News correspondent, took a leave from the network when Schwarzenegger ran for governor in 2003 and announced she was leaving her job a year later because she could not juggle her work as a journalist with her duties as first lady.
Since his election, Shriver has toured the state to promote her tax program and has made the annual First Lady's Conference on Women and Families her signature event. She also is credited with overhauling the California Museum in downtown Sacramento and, with Schwarzenegger, starting the California Hall of Fame.
Last year, she released a book entitled "Just Who Will You Be?"
"I lost a sense of my identity when I left that job a few years ago," she said, referring to her career in broadcasting. "But this job has turned into a great thing for me. ... I like bringing government to the people."
Shriver's father, Sargent Shriver, was the 1972 Democratic candidate for vice president and she is the niece of President John F. Kennedy.
"I've been in public life my whole life," she said. "I'm on a journey to become myself."