This story is part of CNBC Make It's Six-Figure Side Hustle series, where people with lucrative side hustles break down the routines and habits they've used to make money on top of their full-time jobs. Got a story to tell? Let us know! Email us at AskMakeIt@cnbc.com.

Six months ago, Tim Riegel bent over his computer, reviewed his monthly earnings statement and saw that his highly lucrative side hustle was making less money.