I "moonlight" as a productivity coach.
moonlight - (verb) "to work at a second job in addition to your regular job"
Many people begin their work day when the moon rises. In the nineteenth century, the term "moonlighting" related to thieves who stole at night. However, a July 22, 1957, "Time" magazine article gave the term "moonlighting" a new connotation that has stuck: Working multiple jobs. Having a "moonlighter," or second job, has become prevalent today for economical and professional reasons. The U.S. Bureau of Labor Statistics reports that in September 2013 more than 7 million workers held more than one job. - from http://work.chron.com/
moonlighter - (noun) "a person who holds a second job (usually after hours) TFD
"Are you interested in becoming a moonlighter? Are you looking for another job to supplement your income? If so, U-Haul is the right place for ..."
"I'm a dentist by day but I moonlight as a dj."