After a long flight, many of us reach for a sweet treat in search of a much-needed energy jolt. Might an app send you in search of a healthier option, like an apple? A new mobile app called Lark learns your habits over time, and sends you a notification when it anticipates a sugar craving. Lark uses sensors in the smartphone to track your movement and activity, but its truly standout feature is its personal assistant. The app chats with you about your health and fitness goals almost like a real person would ("that's outstanding!" "You've increased your walking today!"). The goal is to motivate you by cheering you on, rather than to admonish you for failing to meet your daily health goal. In 2015, Lark brought its weight loss coach to the wrist with its Apple Watch app, which also sends users notifications to prompt healthy behaviors. It was even named one of Apple's top 25 apps for iOS.