Terrible link. It completely ignores the fact that chronic depression tends to stem from medical or psychological conditions and not 'feeling bad about yourself'.
Articles like that just make the stigma that much worse. And the advice it gives will ONLY help if the depression stems from life events and has no underlying cause.
Would you tell someone with a broken leg to just tough it out and go walking? Someone with a toothache to just try eating different food and the toothache will go away? Then why are you telling someone who could well have a life-threatening medical condition to just go outside and play? If his depression is caused by something other than 'just being sad', all that will do is convince him that 'something is wrong' with him and make the depression that much worse.
First step is to see a professional to see what the CAUSE of the depression is, not send him meaningless and possibly harmful mumbo-jumbo.
What's the difference between primary and secondary depression?
A quick Google search would provide you a wealth of information on the subject, but in general:
Primary depression exists on its own and is not the result of another medical or psychiatric condition. It can also be its own psychological or psychiatric issue, such as
major depressive disorder. Anti-depressants are sometimes used to treat this kind of depression, as one of the causes is the chemical imbalance in the brain I mentioned previously. Other times, it requires extensive psychiatric or psychological therapy, especially if (as in my case) it's tied to another major personality disorder.
Secondary depression is caused by something else - major negative life events, major diseases such as cancer, psychiatric conditions like schizophrenia, etc. The primary thing is that this was CAUSED, as opposed to happening on its own. This is the type that can often be handled with changing your routine and getting some counseling.