2022 · Founder and CEO of social fitness app Corecircle, Nastassia Ponomarenko has helped more than 300,000 people achieve their goals via exercise tracking and connecting with other fitness buffs. The. Founder / CEO Corecircle Apr 2021 - Present2 years 6 months San Francisco Bay Area A social fitness app with 350k+ users that combines community and workout tracking tools to transform people's.