(Most of my coaching is about how to write.)
What is not done remains undone out of laziness or stupidity. We do not take the moment that is required to do it, either from slack discipline or from poor planning.
To call the first "laziness" and the second "stupidity" sounds, perhaps, a little harsh. But I have found that people usually have no difficulty being hard on themselves when they are not making progress. It is just that they prefer to say mean things about themselves when they are not true. They will call themselves lazy when they know they've been stupid, or stupid when they know they've been lazy.
In my coaching we try to face the problem more directly. It normally takes place over an eight-week period of the client's choosing, either individually or in groups. Meetings last either 27 minutes (for individuals) or 54 minutes (for groups) and are normally held at the client's place of work.