At the TWO School by Indimotard and OVERDRIVE, we talk about riding actively, not reactively. It's a very basic level change that riders have to make as they focus on improving their skills. And riding actively - I will explain in a moment - also connects to many of the other things you have read on this page. That includes the idea that motorcycles are mutually exclusive to all other activities when you're riding. That you must anticipate to ride smoother and better. And that you have to decide constantly as to what happens next.
At the very core, you can only do two things to a motorcycle as a rider. You can choose to change direction or alter speed. Sometimes both at the same time. But the acting versus reacting discussion is about how the decision to change speed or direction is made.
For example, let's say a car swerves into your lane with little or no warning. You have the choice to make room to avoid a collision. The closing of the throttle and/or the change of direction to accommodate the idiot in the car happens within an instant. But it is a reaction. A good one will save you, to be sure.
But action precedes that. An active rider thinks, "I'm in the lane with cars on both sides in the other lanes. How do I position myself in here so that no one thinks that they can just swerve in and take my space?"
That changes the game. Because if the answer is that you cannot take a position that protects your space, then the rider must immediately act to find a more secure place. Which could be in the top or left-most lane so that, at least on one side of the bike, the variables are cut down.
This rider is ready to react. But his forward thinking and situational awareness allow him or her to consider future scenarios and work out avoidance methods so that they don't have to react.
How do you learn this? It's hard to explain but it's the difference between "I've maths homework so I've to finish it" and "I'll finish the maths homework now, so I can go ride my motorcycle later."
Thinking actively also improves your concentration, increases your safety margin and most importantly, it reduces the sense of speed so you tend to make better decision based on better sensory input data.
And if you intend to ride a big, fast motorcycle tomorrow, this is crucial. Because you can only ride fast if you can out-think the pace the motorcycle is capable of.