If a car is left in the garage, it’s not running or working. It can harm the car to be used too little, just as it can harm the car to be used too much, or in the wrong way. Your mind, like that car, risks not getting enough of a workout. Passivity signals that it needs a specific focus or challenge other than what you give it. If you’re passive, you’re probably reacting to events in life and thinking about them as they come up. This is fine and necessary. But you also need to actively engage your mind in things that YOU yourself choose—not just things that happen.
As we mature, this happens. More and more goes on in life, largely things of our own creation. Career and personal relationships, as well as responsibilities (big and small) tend to magnify and grow. This can lead to passivity, because as there’s more to confront that comes up in our faces, there’s less of an inclination to actively seek things out, due to lack of time and energy. But we still need to actively seek things out. This can be anything that you choose to engage your mind—from a book, to an intellectual task, to a task around the house (e.g. painting a room, remodeling a room), or a project related either to a serious hobby or your job. The key is that you actively engage your mind.