There a variety of factors that can contribute to depression (like lack of sunlight, no exercise, and poor sleep), but the primary thing that causes depression is how you think about things.
To understand this better, think of it this way: when you don't get enough sunlight, exercise, or sleep, it's like you're building a loaded gun that could go off at any moment. But thinking negatively is what actually pulls the trigger and causes the depressed condition.
To fully understand this, appreciate what steps a cruel person would take to deliberately make somoene else depressed.
Let's say that a sadistic, cruel person wants to take the happiest person in the world and make him depressed as quickly as possible. To set the stage for depression, he takes the following steps used by torturers around the world:
Even though the sadistic torturer doesn't physically strike his poor victim, he creates conditions that are already more than enough to make his victim absolutely miserable.
But for his victim to actually become depressed, something important has to happen: his victim has to begin thinking in depressing ways.
Think about it: even though this poor victim is in a nightmare environment, he could still think that he's strong enough to handle all of this, and that he will ultimately prevail no matter what is done to him.
With these kinds of thoughts, the victim is still mentally "up" and not depressed. He still has a lot of fight and life left in him, which helps him keep his head held high.
But the torturer bets that his poor victim will soon think the following kinds of thoughts: his life is awful, his situation will not improve, and that he can't go on any further.
When he starts thinking this way, the poor victim officially becomes depressed. The life goes out of him, his shoulders sag, and he becomes very much like a deflated balloon that has lost all its air.
This torture example is designed to show you that while there are a lot factors that contribute to depression and set the stage for it, your thoughts are what actually cause you to be depressed.
To understand just how important your thoughts are, imagine that every day you get plenty of sunlight, lots of exercise, socially interact with others, eat a healthy diet, and get plenty of sleep.
However, you continue to think that your life is awful, and that you'll never be truly happy.
With this scenario, you will remain depressed, and all the exercise and sunlight in the world won't matter.
After all, your depressing thinking trumps everything. (In this example, it's like you're making a healthy drink every day, but then lacing it with poison. So it does you no good.)
Already, you can probably tell that the smartest strategy for eliminating depression is to do things that make it easier for you to stop being depressed (like getting plenty of exercise, sleep, and sunlight), but to especially focus on changing thoughts that make you depressed.
Indeed, the power of changing your thinking is far more powerful than any antidepressant ever created. This has been clinically proven in every drug trial ever conducted, via the placebo effect.
Since changing your thinking is so powerful and beneficial, the next step for you is to learn more about the placebo effect, and why it proves without a doubt that the most important thing you can do to eliminate depression is to improve your thinking.
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