In the name of “critical thinking,” I have noticed a tendency in the West for intellectuals to become not only reflective and deconstructive, but to frequently live in mentally aggressive/hostile, cynical, pessimistic, etc. states of mind. Although I would agree that being overly positive can bias one in various ways (e.g., to see only what you want to see and miss/ignore challenges, obstacles, etc.), being overly negative can bias one in opposite ways (e.g., to see only obstacles or challenges and miss/ignore what might be possible). So I think it is important to turn critical thinking against itself, and to be critical of becoming too negative of a person. To me, the main value of critical thinking is to acknowledge and let go of biases and assumptions, to become mentally detached and aware, to try to see and think clearly. Mental detachment is perhaps the primary activity/aspect of mindfulness meditation, as is awareness of vipassana meditation.
Cramming your head full of knowledge or thinking as quickly as possible (i.e., becoming as robotically intelligent as possible), is not the same as mental development (e.g., practicing self-control, concentration, mindfulness/awareness, virtuous thoughts, etc.). Meditation (in Buddhism) means working to stop or to control thoughts and feelings, to become a better person.
The easiest way that I find to quiet the mind is to want to have a quiet mind, to value the ease and openness of it, and to choose to make only as few thoughts and feelings as necessary. Making thoughts and feelings, running around doing things, etc. requires energy and struggle. To feel less tired and stressed, minimize the things you have to consider or make/do; consider and do things more reluctantly. Having a quiet mind also allows one to see more details in the world, in a less filtered way.
Why did your current thought come into your head? Are you aware and mindful enough to know what prompted/conditioned it?
“As we meditate, we’re working on a skill, and the skill is to bring the mind to a state of stillness, with as much alertness and awareness as possible, because this skill lies at the basis of all other skills. If you want to be skillful in how you act, how you speak, how you think… you need to be aware of what you’re doing, and you have to be in the present moment, to watch your intentions, because your intentions shape everything” (Thanissaro Bhikkhu, “The Skill of Meditation“, 11/29/2016).