Comfort is a strange thing. We spend most of our lives seeking it, but many of the greatest thinkers throughout history warn against it. They obviously never met my cat.

To make a goal of comfort or happiness has never appealed to me; a system of ethics built on this basis would be sufficient only for a herd of cattle
-Albert Einstein

The superior man thinks always of virtue; the common man thinks of comfort.
-Confucius

The ultimate measure of a man is not where he stands in moments of comfort and convenience, but where he stands at times of challenge and controversy.
-Martin Luther King, Jr.

And many modern motivational speakers assign it to a “zone” to avoid:

Move out of your comfort zone. You can only grow if you are willing to feel awkward and uncomfortable when you try something new.
-Brian Tracy