There are a handful of apps designed to help you develop new habits by keeping an unbroken chain going over the course of days. This one is the best, and well worth the cost considering how even an incremental improvement in effectiveness of habit development can have a major positive impact on ones life. The watchOS app is also one of the few that I find both useful and usable. The watch complication is particularly well-thought out and effective.
CommLag about Streaks, v1.7.3