Cadoo, a US startup, gamifies fitness with its app by allowing users to stake money in challenges tailored to various fitness goals. Launched in 2018 and supported by $1.5 million in seed funding, Cadoo offers public challenges weekly and is introducing private challenges for individuals, families, friends, and groups. The app verifies activity through popular fitness trackers and apps like Strava, Fitbit, and Apple Health, fostering motivation and community engagement.