Background: Ryan was born in Refugio, south of Victoria in south Texas, the youngest of six children, to Lynn Nolan Ryan Sr. (1907-1970), and the former Martha Lee Hancock (1913-1990). The senior Ryan operated a newspaper delivery service for the Houston Post that required him to rise in the early morning hours to prepare 1,500 newspapers for delivery over a 55-mile route. The children were expected to help with the daily tasks.
Context: Nolan Ryan's post-retirement business interests include ownership of two minor league teams: the Corpus Christi Hooks, which play in the Class AA Texas League, and the Round Rock Express, a Class AAA team in the Pacific Coast League. Both teams were affiliates of the Houston Astros, for whom Ryan also served as a special assistant to the general manager until selling his interest in the team in the off-season between 2004 and 2005. He became the president of the Texas Rangers in 2008. The Express became the Rangers' AAA affiliate beginning in 2010; the Hooks are still the Astros' AA affiliate and were purchased by the Astros in 2013 when Nolan's son, Reid Ryan, took office as President of the Houston Astros.  Ryan threw out the ceremonial first pitch before Game 3 of the 2005 World Series between the Astros and the White Sox, the first World Series game ever played in Texas. That game went 14 innings, equaling the longest in innings in World Series history (at 5:41, it was the longest in time). ESPN wryly suggested the Astros might have needed to pull the 58-year-old Ryan out of retirement if the game had gone much longer.  Ryan has co-written six books: autobiographies Miracle Man (with Jerry Jenkins, 1992), Throwing Heat (with Harvey Frommer, 1988) and The Road to Cooperstown (with Mickey Herskowitz and T.R. Sullivan, 1999); Kings of the Hill (with Mickey Herskowitz, 1992), about contemporary pitchers; and instructional books Pitching and Hitting (with Joe Torre and Joel Cohen, 1977), and Nolan Ryan's Pitcher's Bible (with Tom House, 1991).  In addition to his baseball activities, Ryan was majority owner and chairman of Express Bank of Alvin but sold his interest in 2005. He also owned a restaurant in Three Rivers, Texas. He served on the Texas Parks and Wildlife Commission from 1995 to 2001. He appeared as a TV spokesman for Advil for several years, promoting the pain medication he recommended for his own arm. He also has appeared in various television commercials shown in the Texas market.  After retiring from baseball, Ryan teamed up with the federal government to promote physical fitness. His likeness was used in the "Nolan Ryan Fitness Guide", published by The President's Council on Physical Fitness and Sports in 1994. Ryan suffered a heart attack on April 25, 2000, and had to receive a double coronary bypass.
Question: what did he retire from?

Answer:
After retiring from baseball, Ryan teamed up with the federal government to promote physical fitness.