My approach to what I do in my job — and it might even be the approach to my life — is that everything I do is the most important thing I do. Whether it’s a play or the next film. It is the most important thing. I know it’s not going to be the most important thing, and it might not be close to being the best, but I have to make it the most important thing. That means I will be ambitious with my job and not with my career. That’s a very big difference, because if I’m ambitious with my career, everything I do now is just stepping-stones leading to something — a goal I might never reach, and so everything will be disappointing. But if I make everything important, then eventually it will become a career. Big or small, we don’t know. But at least everything was important.
A theory of change is the opposite of a theory of action — it works backwards from the goal, in concrete steps, to figure out what you can do to achieve it. To develop a theory of change, you need to start at the end and repeatedly ask yourself, “Concretely, how does one achieve that?”
As for how to write well, here's the short version:
Write a bad version 1 as fast as you can;
rewrite it over and over;
if you can't get started, tell someone what you plan to write about, then write down what you said;
expect 80% of the ideas in an essay to happen after you start writing it;
start writing when you think of the first sentence;
write about stuff you like;
learn to recognize the approach of an ending, and when one appears, grab it.