How Can I Stop My Depressing Thoughts?

Question: What can I do when I become depressed and even think of harming myself?
Response: Dwelling on the painful things in our lives can lead us into depression and even suicidal thoughts. But suicide only delays and increases the suffering, and does nothing to end it.
When I was young, I had appendicitis. As we were getting ready to leave for the hospital, I don't remember whether my father took my hand or I asked him to. But I clearly remember asking him to squeeze my hand, hard. The pain from the appendix was excruciating. But I realized that my father's squeezing my hand to the point it hurt (I can only imagine how difficult this must have been for him) took my mind off the pain from my about-to-burst appendix.
I could not focus on both at the same time.
This memory came to me when I read the following by Ven. K. Sri Dhammananda in How to Overcome Your Difficulties:
'“A noted British anatomist was once asked by a student what was the best cure for fear, and he answered, ‘Try doing something for someone.’ The student was considerably astonished by the reply, and requested further enlightenment whereupon his instructor said, ‘You can’t have two opposing sets of thoughts in your mind at one and the same time.’ One set of thoughts will always drive the other out. If, for instance, your mind is completely occupied with an unselfish desire to help someone else, you can’t be harbouring fear at the same time.”
Our feelings arise from what we tell ourselves. Trying to break negative thought patterns is very difficult, but this is what our practice seeks to do: to replace what is bad with what is good. Since we all have our own karmic pasts and habits, we each need to find what works for us. But essentially, we need to break into the current line of thoughts with something that pulls our mind away from what is bothering us.
Essentially, Ven. K. Sri Dhammananda, the anatomist, and I are saying the same thing: replace negative thoughts with positive ones.
If I can replace one depressing thought with just one caring thought, I will have begun to turn my mind away from sadness or depression towards happiness. And with more of my thoughts arising from my caring for others, my own state of mind will be more firmly rooted in happiness.
Is this easy?
Of course not.
Is it possible and worthwhile?
Definitely!
Essence of the Infinite Life Sutra, Excerpt Thirty-three
People in the world strive for things of little urgency. Amidst extreme evils and severe sufferings, they diligently work . . . dictated by their minds. . . . Whether they have or do not have, they worry.
“People in the world strive for things of little urgency.” “People in the world” refers to the beings in the Six Paths. “Of little urgency” means of no importance. The beings in the Six Paths all busy themselves with unimportant things and forget the important things such as (1) knowing the truth of life and the universe, (2) understanding the transmigration within the Six Paths, and (3) transcending the Six Paths.
“Extreme evils and severe sufferings” are karmic results. “Extreme” means severe. “Severe evils” refers to the Ten Evil Karmas: the physical karmas of killing, stealing, and sexual misconduct; the verbal karmas of false speech, divisive speech, harsh speech, and enticing speech; and the mental karmas of greed, anger, and ignorance. As the Ten Evil Karmas increase continually, they are called “extreme evils.” When one commits such extreme evils, how can one not suffer retribution! Great suffering is transmigration within the Six Paths; small suffering is the suffering in one’s present life, from birth to death.
“They diligently work . . . dictated by their minds.” “Mind” refers to greed, anger, ignorance, deluded mind, and wandering thoughts. In this kind of environment, people work hard and busy themselves every day simply out of “greed, anger, ignorance,” and for “fame, prestige, gain, wealth,” the Five Desires, and the Six Dusts.
“Whether they have or not, they worry.” When one obtains something, one is afraid of losing it. When one does not have something, one craves it. So one worries both ways: when one has something and when one does not. This is the true picture of society and the world presently.
~ Essence of the Infinite Life Sutra by Venerable Master Chin Kung