Retired slugger Doug Gredvig covers all the bases while growing a restroom business from startup to big success.

For years, Doug Gredvig made a living wearing a baseball jersey and cleats, playing first base for minor league affiliates of the Baltimore Orioles. Today, he still competes every day, but he wears a uniform for a different squad: the team at Area Restroom Solutions, the portable restroom outfit he founded in Sacramento, California.

The jump from curve balls and umpires to vacuum trucks and portable restrooms may seem lik