Many people today use the term "critical thinking" to mean a valued ability to doubt, to question, to investigate. So, schools sometimes use the term to describe habits of thought they want to see in their students. I agree that being a good questioner is a mighty important skill. Maybe you buy the statement often attributed to Socrates that the unexamined life is not worth living. The person who can employ critical thinking can question his own life: What am I living for? Why do I live? What do I want? Why do I want that and not this? What has been the result, so far, of wanting that? What do I expect my life will be like once I get that? Why do I expect that? Are my expectations reasonable or overly whimsical and far-fetched? It often pays off well to apply my critical thinking skills to my own life.
However, I often meet people who seem to be without much foundation in their lives. If you have a foundation, you can examine it critically but also gratefully and maybe helpfully and profitably. Any way or any source or foundation you can build may serve as a welcome anchor or sanctuary when you need one.
The philosopher and spiritual leader Eckhart Tolle sometimes emphasizes that thinking, as in critical thinking, or as in typical thinking, can be overdone. Some people using an Eastern approach recommend consciously labeling thoughts as "thinking" for some part of each day. Such a practice can emphasize that our lives, our bodies, our relationships are more than thoughts. We are flesh and we are animals. We do require food, shelter, clothing, warmth, motion, and air. We have many requirements and many desires, such as a big-screen tv and a chance to visit Maui.
As a grown-up these days, I can live more fully if I can step back from my mind and observe it. This activity is similar to critically thinking about my mind and what it suggests and thinks but there is a difference. Good mind observation involves low levels of criticism and negative judgment. It means backing up a step and seeing as much of the forest as possible while still noting the trees themselves. Since I really am the product of millions of years of life experience and design adjustments, it makes sense to me to give myself plenty of credit. My conscious mind may become impatient with my shoulder or the fact that it is raining again but my observer of myself realizes that impatience, boredom, fear, piggy desires are all planned into me and maybe have a place that I can't fully appreciate.
So, one sign to me of a well-furnished mind is that it can and does apply a little doubt to its own desires, worries, boogey men, certainties. Such a mind notices that its ideas are only ideas, that thoughts can be valuable but also misguided, outlandish but also inspirational and while noticing that, keeps on living, doing the laundry and voting and getting the oil changed.