“You have a trigger — a person needs an external trigger to think about opening your app. For Tinder it's a feeling: I'm bored or lonely. For us we didn't have an emotion, but we did have the need for reminders, and so we leveraged push notifications very heavily.”

Apps without an emotional trigger have to manufacture one

Alex frames retention as trigger plus delivered value. Apps without an inherent emotional pull (Tinder = boredom/loneliness) have to engineer one. For Greg, push-notification water reminders became the external trigger — the app is the trigger, and the user comes back because the trigger arrives.