Depression is a phenomenon of discontentment. Why does this phenomenon exist? The reason is that every person is born with an unlimited desire for enjoyment. But, everyone has very limited capacity of fulfilment. It is this gap in human nature that makes people live in unrest. Is this phenomenon due to a defect in nature? Not at all. It is due to man's unawareness of himself that creates this problem. Selfawareness is the key to a contented life, while unawareness leads to all kinds of discontentment and restlessness.
A common phenomenon seen these days is that people live in tension and stress. A person who is in tension can never take a sound decision. This is why, people should be tension-free.
Why do people have tension?
The greatest reason for tension is haste. People want to do a lot of work quickly. An industrialist wants to become a billionaire. So in the beginning he will take a huge step so that within a year he can become a billionaire. Then he will live in tension. Because his work will become unmanageable. If you make steady progress, proceed gradually and do what you can manage, then you will not have tension. Tension is the result of increasing one's work load so much that it becomes unmanageable. The secret to tension-free living is to work within your manageable limit. This is the formula of life.
This has been mentioned in a hadith: Copy Arabic text (Sunan al-Kubra, al-Bayhaqi, 20270)
Patience is from God and hastiness is from Satan. A person who makes haste and wants to instantly go ahead is under the influence of Satan. Keep this in mind. This is true even if you do a good deed, or you do a bad deed. If you have to do a good deed, Satan will try to influence you. Satan will try to activate your mind. He will try to make you do what is unmanageable. You will live in tension and not be able to do anything. If you are building a mosque, Satan will tell you to build it quickly. He will want you to quickly make a 5-storey building. In this way, you won't be able to do anything. You will only live in tension. Patience is from God and hastiness is from Satan. You should work within manageable limit, so that you don't have to live in tension.
Don't let your work become unmanageable. This will make you tensed. You will become a victim of Satan.