Your primary job in Michigan may not be enough to pay the bills, or you may not have enough money to put aside savings for a planned purchase, retirement or emergency. If that is the case, you may take on a second job to make up the difference. According to The Motley Fool, the term for this is a side hustle. Anyone, at any age, can take on a side hustle despite a stereotypical association with millennials. The top-earning age group for side hustles is people aged 53 to 62.