“The mind is like an umbrella. It’s most useful when open.”
If you don’t make a regular practice of finding and opening your umbrella, it won’t be ready to go when you need to use it. The same goes with your mind; one must cultivate openness and practice expanded thinking if you want to be ready when the time is right.
The key to practicing openness of mind is to ask yourself the important “why” questions regularly. Why do I believe what I believe? Why is that belief correct? Why is that belief useful? Etc.
If you don’t ask yourself “why,” you might find that your umbrella is frayed and useless when called into service.