A habit is something that you do often and regularly. sometimes without knowing that you are doing it. Writing at a specific time daily, in a specific place are habits that help develop writers and produce a meaningful body of work to be proud of.
It is more rational that we set habits than goals. Effective habit building helps us to achieve goals. For instance, instead of having a goal of creating a best seller as your first publication, one can create a habit of writing everyday. Writing everyday allows for a drip process of building a body of work, developing writing skills and shipping work on a regular. The habit of doing the things mentioned is more sustainable than just having a goal of creating a best seller.