Great question! 

The Keep-it-up feature is all about creating new good habits. 

Studies show that a new habit can be created in anything from 14 to 88 days (!). 

We recommend you keep up an action 21-28 days - for simple actions that's often how long it takes

But it all depends on the action - how easy it is to make part of your life, how often you do it, how small it is, etc. so stick to it until it feels effortless!