SAN RAMON, CA -- Mark Mastrov, the founder of 24 Hour Fitness, has resigned as the company’s chairman of the board, effective Jan. 31, according to a company statement sent to Club Industry’s Fitness Business Pro.

Mastrov, who founded 24 Hour Fitness in 1983, plans to pursue other opportunities, according to the statement.

“Mark Mastrov has provided solid leadership to our company for the past 25 years,” 24 Hour CEO Carl Liebert said in the statement. “His commitment has made a lasting impact on not only our company, but on our industry as well. The board of directors and I wish Mark the best in his future endeavors.”

Mastrov moved to the chairman of the board position in 2006 after Forstmann Little & Co. named Liebert as its new chief executive officer. The move came a year and a half after Forstmann Little & Co. purchased 24 Hour for $1.6 billion.

Previously, Liebert served as executive vice president at The Home Depot, where he was responsible for sales, execution and operation. He also had served as senior vice president, operations for The Home Depot.

24 Hour grew from a one-club company into the highest-revenue producing company in the fitness club industry. 24 Hour serves more than 3 million members in more than 400 clubs worldwide.