Kayla Itsines became a millionaire at 22 and sold her fitness app for $400 million—buying a gas station paid her rent

A millennial entrepreneur has reeled in millions from her success as a fitness influencer, but now she’s making bank and paid her rent through another unlikely source: a gas station. 

Australian fitness mogul Kayla Itsines has built an exercise empire over the past decade, amassing 15.6 million Instagram users tuning into her content. 

The influencer first tasted success with her 12-week “Bikini Body Guide” (BBG) fitness program—a business model she cofounded and bootstrapped, which launched her to self-made millionaire status at just 22 years old. The serial entrepreneur then rebranded the venture to a personal training platform Sweat App, which garnered an online community of 50 million members. And just six years later, Itsines sold Sweat to fitness platform iFIT for a whopping $400 million.

Many might expect entrepreneurs who sell their companies for millions t...