When a young comedian asked Jerry Seinfeld for advice on how to be a better comedian, Seinfeld asked him to pick up a calendar and start marking an X on every day that he writes new jokes. The idea being that this forms a chain (or a streak) over time. And the goal from that point on, is to simply not break the chain.

It is easier to get into the habit because it it easier to come up with new things while starting off. But, it gets progressively harder with each passing day. 

And therein lies the challenge. We have to get better to keep the chain going. We have to improve.

And that is how the advice works.