We tend to focus on what business people call the “lag measures” - the things we can’t measure immediately. E.g., focusing on a number of sales by the end of the year vs. focusing on the work you put in a day.
If a writer is focusing on the end result - the book - she’s focusing on a lag measure. If she’s focusing on pages written per day, then she’s focusing on the lead measure. One you can measure, the other you can’t. Well, you can, but the time you can - it might be too late.
Lag and lead measures are everywhere. E.g., when you eat junk food, the results are lagging - that is, the time you see the results of the unhealthy eating become visible when the damage has already been done. The same applies to exercise, smoking, drugs, working on your craft, spending time on social media, etc. The result is not instantly visible.
So, when we want to get work done, it’s best to focus on how much did we get done in one day - not on the end product itself. Because we can easily measure the work, we put in at a given day and immediately know if we are in schedule or not.