Taking the idea you suggest of “I don’t think about alcohol. Here’s what I think about instead. I don’t think about what I’m going to eat all the time, here’s what I think about instead.” I try to apply it to my writing but it doesn’t seem to work as smoothly as with alcohol and food.

I am an aspiring writer and am currently always thinking about:
How much more I still need to write to finish this piece?
Have I written enough today?
Have what I written is good enough today?

So before I will be able to make a successful living as a writer, I can’t really understand what will I be thinking if I already, say, written two books.

Wouldn’t I still be thinking I need to continue writing? Other published writers who see writing as their job still get up each day and think about those things.
They may be also thinking, ‘I have a meeting with my agent today, I have a book tour coming,’ but it’s irrelevant for me to think about that now.
Not sure I can use this for writing. Is this only for over-eaters and over-drinkers?