Indianapolis coach Tony Dungy has contemplated stepping down in recent seasons. ((Andy Lyons/Getty Images))

Tony Dungy announced his retirement Monday after seven seasons as coach of the Indianapolis Colts.

Jim Caldwell, currently an assistant with the Colts, will take over from Dungy.

"These seven years have been better than I could ever have imagined," Dungy said at a news conference. "I just have to thank everyone."

Dungy, 53, guided the Colts to the Super Bowl in 2006 but the team has been defeated in its first playoff game each of the past two seasons.

Indianapolis fell to San Diego last week after winning the previous eight games of the regular season.

Dungy had contemplated his coaching future after each of the last five seasons.

"We just felt this was the right time," Dungy said. "Don't shed any tears for me. I got to live a dream most people don't get to live."

Over 13 consecutive seasons as an NFL head coach, Dungy is 139-69, putting him 18th on the all-time wins list.

He led Tampa Bay for six seasons prior to joining the Colts, with the Buccaneers winning the Super Bowl the season after he left.

Dungy leaves as the Colts' franchise leader in victories.

He went 85-27 in the regular season and 7-6 in the playoffs, including the victory over Chicago in the 2007 Super Bowl.

Dungy was a defensive back for the Pittsburgh Steelers in the 1970s, later serving as an assistant with the club before ascending the coaching ranks with subsequent jobs in Minnesota and Kansas City.

After becoming the first African-American coach to win the Super Bowl three years ago, Dungy wrote Quiet Strength: The Principles, Practices, and Priorities of a Winning Life, which reached the top spot on the New York Times nonfiction list. 

The book dealt with Dungy's personal and professional life, including the 2005 suicide death of his teen son, James.

With files from the Associated Press