Mom could have been depressed based on her life’s circumstances. One of the reasons Mom was who she was flowed from what she read. What she read saturated her mind and became, I believe, the source of her own inner conversations. It is true that what flows from the mouth comes from the heart. What you treasure in your heart and put in your heart informs your thinking, choices, words, attitudes and even the way you “talk to yourself.”

Mom was often reading something.

We all talk to ourselves. We even have conversations with someone or rehearse conversations before the words come out of our mouths. Perhaps we ought to give more thought to what we put in our hearts and do more talking to ourselves than listening to our uninformed or misinformed selves.

Christian Psychologist Phil Monroe quotes Martyn Lloyd-Jones regarding listening to yourself and talking to yourself:

I think Martyn Lloyd-Jones gets it right when he tells his readers (Spiritual Depression, pp 20-21) to take charge of their thinking by talking back to their feelings rather than passively listening to their own feelings. In many respects, this is what the author of Psalm 42-43 is doing. This is good medicine, if taken on one’s own. Probably not so good if forced down the throat of another…

“I say that we must talk to ourselves instead of allowing ‘ourselves’ to talk to us! …Have you realized that most of your unhappiness in life is due to the fact that you are listening to yourself instead of talking to yourself? …The essence of this matter is to understand that this self of ours, this other man within us, has got to be handled. Do not listen to him; turn on him; speak to him; condemn him; upbraid him; exhort him; encourage him; remind him of what you know, instead of listening placidly to him and allowing him to drag you down and depress you.

Why are you cast down, O my soul, and why are you in turmoil within me? Hope in God; for I shall again praise him, my salvation and my God.Psalm 42:11