Perhaps this short description will resonate with you: It's like a dark cloud hanging around and in my head, and there is this feeling of general lack of energy and interest, plus a background sense of fear.
This inner experience is very common - it can be short-lived, come and go, or we may become possessed by it - and then it becomes a longer term and far more serious problem. But why is it there in the first place?
The short answer is that our mind becomes overshadowed by powerful repetitive thoughts which change our perception of life and the world.
If we explore inwardly, we can see how this happens...
Look now - when a thought arises, your attention goes to it automatically and instantly. There is 'your attention' and the thought - and attention is just suddenly in the thought.
We often deliberately create thoughts, but most just surface as if from nowhere, like they have a life of their own! And when a thought is a powerful one, it takes us over, almost like we become possessed by it. This happens because thoughts and feelings are in fact energy. We may not be able to sense thoughts at energy, but that's what they are. This is not some 'spiritual concept', it is a scientifically proven reality.
Happy or joyful thought/feelings have an uplifting quality - a high vibrational energy. Difficult or painful thought/feelings have a downward quality - a low vibrational energy.
Depression is a state where we are possessed by low vibrational energy.
So, what to do?
There are psychological techniques, tools, therapies, and even chemical interventions, which can help to alleviate symptoms and sometimes resolve a particular issue, but a permanent resolution of the underlying cause, only comes after we have broken the lifelong habit of connecting with the energies of thought/feelings.
We must break the habit by creating a new one.
We start by establishing a practice of moving attention away from low vibrational energy as soon as it arises in our conscious awareness.
There is a practice that can be learned which makes this possible - it is actually very simple - but it is not a quick fix and does require commitment and perseverance.
The practice is explained in a spoken contemplation you can listen to by clicking here.