Aussie fitness entrepreneur Kayla Itsines sells Sweat app for $400 million SWEAT co-founder Kayla Itsines. Kayla Itsines’ Sweat app has sold to US fitness tech company iFIT for a reported $400 million, bringing the app she founded from her Adelaide garden to an even broader global audience. Sweat was founded in 2015 by Itsines and then-partner Tobi Pearce, following the launch of a fitness e-book. It has since grown into a fitness sensation, reaching a community of more than 50 million people across its social channels and app. Now a team of 13 trainers offer some 5,000 workouts and 26 exercise programs. The app is available in eight different languages, across 155 countries.