I think it is a very healthy thing to pretend that all private discussions are public, thinking "what if my mother (pastor, friends, family, neighbor, etc.) were listening?"
I'm reminded of many stories I've heard (and even experienced first-hand) of people being greatly hurt by hearing conversations that occurred when the speakers didn't know that others really were listening.
All our words and even our private thoughts are heard by our Father in Heaven. That in itself should be enough to temper all our doings.
With that in mind, listen to Thomas á Kempis, in The Imitation of Christ:
The Tenth ChapterAnd again, listen to this:
Avoiding Idle Talk
SHUN the gossip of men as much as possible, for discussion of worldly affairs, even though sincere, is a great distraction inasmuch as we are quickly ensnared and captivated by vanity.
Many a time I wish that I had held my peace and had not associated with men. Why, indeed, do we converse and gossip among ourselves when we so seldom part without a troubled conscience? We do so because we seek comfort from one another's conversation and wish to ease the mind wearied by diverse thoughts. Hence, we talk and think quite fondly of things we like very much or of things we dislike intensely. But, sad to say, we often talk vainly and to no purpose; for this external pleasure effectively bars inward and divine consolation.
Therefore we must watch and pray lest time pass idly.
When the right and opportune moment comes for speaking, say something that will edify.
Bad habits and indifference to spiritual progress do much to remove the guard from the tongue. Devout conversation on spiritual matters, on the contrary, is a great aid to spiritual progress, especially when persons of the same mind and spirit associate together in God.
Chapter 9Thomas á Kempis' last name was Hämerken, "Little Hammer." I consider him a big hammer, because his writings convict me of so much that is sinful within me. For that reason I find it beneficial to read him.
On Obedience and Discipline
It is an excellent thing to live under obedience to a superior, and not to be one's own master. It is much safer to obey than to rule. Many live under obedience more of necessity than of love and such people are often discontented and complaining. They will never attain freedom of mind unless they submit with their whole heart for the love of God. Go where you please, but nowhere will you find rest except in humble obedience under the rule of a superior. Preference for other places and desire for change have unsettled many.
Everyone gladly does whatever he most likes, and likes best those who think as he does; but if God is to dwell among us we must sometimes yield our own opinion for the sake of peace. Who is so wise that he knows all things? So do not place too much reliance on the rightness of your own view but be ready to consider the views of others. If your opinion is sound, and you forego it for the love of God and follow that of another, you will win great merit. I have often heard that is safer to accept advice than to give it. It may even come about that each of two opinions is good; but to refuse to come to an agreement with others when reason or occasion demand it is a sign of pride and obstinacy.