I hear this line a lot in self-improvement circles. "And then I realised, it's an inside job! Wow!"
So for people whose first language is not English, here's a quick explanation. "an inside job" traditionally referred to the idea of a crime that has been committed, at least partially, by people associated with the victim of the crime - so for example, an inside job might be a bank robbery where employees of the bank are part (or all) of the gang. So detectives in popular culture might say "we suspect it was an inside job" and of course the audience already knows it was, so that adds to the excitement.
In that way, it became something of a cliche or trope, that when you hear of a crime being committed, you might usually take it at face value, that these people were robbed by some other people, but it turns out that no, it was a disgruntled employee of the robbery victim, who were doing the robbing - shocking!
So switch then to someone realising that although their alcoholism is something that they need help with, it's not all of the people, places and things in their life that need to change, it's them, it's an inside job and it has been all along. It's your insides that need to be altered, your thoughts, decisions, feelings. When we talk about "doing the work" this is the work that needs to be done. We need to take a good look at ourselves, admit where we've been going wrong, decide that we're going to live differently, find some forgiveness and repair any damage we might have done along the way. That's hard. It's not nearly as straightforward as it sounds when I write it out in a single sentence. And it can take a long time to put everything right.
But there's no work more worth doing.
What I then think is fascinating is taking it round another loop and looking at the movies about the "inside job" as a metaphor for the damage we do to ourselves. Deep down, we know that the villain behind our personal misfortune (or the villain behind the villain) is within us, it's our thinking and activities that have lead to our own downfall. That's why the story is so popular, because even if you haven't clocked it yet, it's probably true for you too.