Clinical depression is not a behaviour that can be modified. You simply cannot give up depression. If you have a leg in a plaster, you cannot simply decide that you don't have a broken leg.

First of all, what is depression. Is it some kind of permanent miserable state where the person is a perpetual gloom merchant?

In fact, depression is a big umbrella word for various states of sadness. Some people are shy and cautious but that does not necessarily mean that they intend to stay that way - they are trying to get to know their environment and once they are comfortable with it, will socialize with their friends and perhaps fall in love.

There are many reasons in the world to be sad. And it is certainly better to acknowledge these feelings, find the reason and find reasons to be cheerful. Happiness and sadness are part of the human condition. None will blame you for being sad from time to time.

Mild depression can be modified with cognitive therapy, often they are the result of a crisis in life (trauma, bereavement). .
Severe and clinical depression, I'm afraid to say is not the feeling of being sad or even coping with a loss, because it is caused by a chemical imbalance - often triggered by other illnesses - and far from fueling a certain Weltschmerz/Angsty poetry, it prevents you from doing anything because there is simply not enough energy left. Someone who has a serious bout of depression lives through symptoms of permanent fear, so physical symptoms such as stiffening muscles and jumping out of your skin are followed by periods of intense fatigue. I try to counter-act my depression with an educated mind, some rituals such as language exercises, get some sunlight and minimize physical and intellectual fatigue, and yet, one trigger and actually, for a depressive having violent things happening to you just confirms that you have to stay permanently on your guards. I tend to get tired easily because of low thyroid and the Crohn's and that's why some day-to-day activities become a drag. I am not sure, but I think all my symptoms that I have are linked as I don't metabolize things properly, notably iron and B12. You can see that exercise would defeat the purpose because my reserves would be more depleted. Walking is fine because it helps coordination and breathing. Medication helps.

For a long time, the explanation for many diseases was 'psychosomatic', basically you are such a neurotic that your body suffers the effects of it. The approach these days is that many psychological conditions, temporary or permanent are symptoms of an organic illness.

If someone was living with me, I would tell them not to use bright lights, turn the TV down and keep their voice at normal level. If you lived with me, you would end up like Stella from Great Expectations and though not necessarily end up with depression but become very miserable. Or perhaps you would take over my life, and I would say it's alright because I don't have much energy. This is why people with depression, like other disabled people learn to live independently with their illness, find solutions to the obstacles and whilst clinical care is not necessary, a network of professionals need to come and check out on the welfare of their patients. I am lucky that I am articulate, so I can write down how I feel.

The pernicious thing is that there are days where one feels fine and goes out and then you get labeled as a fake because as a depressive you are not supposed to smile. But many permanent depressives display what is known as 'smiling depression'.

You don't want us to be miserable. So we appear happy, even fluffy. We craft our sentences and if you come to visit us, we tidy up the house. Tell us to snap out of our depression, we will oblige until we get tired and need to hide. And when we are ill, we make vague excuses so that you don't worry because we really don't want anyone around for too long because you make us tired. We are not keen on relationships, because we live in fear that you might hurt us or worse, abandon us. So we don't want you in our life in the first place and yet we know that no person is an island.

Like any other illness, it is possible to live with depression and it does not always end up with suicide.

Please don't get depression and being a gormless misery mixed up. When you are sad, you are sad and will be so for a while until it passes - but I do not wish you any form of depression.

There are days when I feel that falling asleep and never waking up again would be a deliverance. And I will have to put up with these thoughts for the rest of my life. The nightmares never vanish, the fight between normality and depression is exhausting. I am writing this because you might have been diagnosed with depression or you might want to know more about it.  x

further reading:
Depression factsheet by NHS