"No principle of life was more constantly emphasized by the Great Teacher than the necessity of right thinking. To Him, the man was not what he appeared to be outwardly, nor what he professed to be by his words: what the man thought determined in all cases what the man was. No teacher emphasized more strongly than He the truth that 'as a man thinketh in his heart, so is he' [Prov. 23:7]....
"Contentment, complacency, peace—all that makes life worth living—have their source in the mind of the individual. From the same source spring unrest, turbulence, misery—everything that leads to dissolution and death....
"It is well for [every teacher and officer in the Church] to pause frequently and take stock of himself to ascertain 'what he is thinking about when he doesn't have to think,' for 'what he thinketh in his heart, so is he.'"
- David O. McKay, "'As a Man Thinketh... ,'" Instructor, Sept. 1958, 257-58; see Ensign, Oct. 2001, p. 22
Click here to read the full article
I am intrigued by the concept of "right thinking." The implication is that there is such a thing as "wrong thinking," that we should be aware of and careful to avoid. President McKay also seems to be warning about the way our thinking impacts our outward appearances or activities. We can appear to be doing the right things at times, professing to be on track; sometimes we are even outwardly deceptive in hiding what is really going on inside. But President McKay reminds us that what goes on in our minds and in our hearts is what really matters. And that ultimately, the things that truly make life worth living and joyful, spring from that hidden inner source:
President McKay suggests each individual should regularly consider "what he is thinking about when he doesn't have to think" as an indicator of the state of our heart. I think the Spirit confirms "right thinking" as it happens as well; if we are willing to be careful and sensitive, we will know if we are on the right track or not.