3. Look at the big picture—all the earth. Question all assumptions
This too is expressible in many ways. We all are forced to make assumptions, often without realizing it. Usually we assume that the world will continue on the trajectory that we see now.
In addition, we can only see anything from our own point of observation. Trying to get away from that and seeing how we look, or how what we are doing looks, from many different perspectives is a real art that takes practice.
One mental trick that may help is to think of earth as a big, finite spaceship, and how we would regard it if it were small enough that that perspective was obvious.