Depression touches everyone at some point. With myself, it is either a major life change, frustrated goals, having so many responsibilities that I can’t keep up, or even just bills that have just gotten out of control.
It’s all-right to be sad, you *need* to feel sad when a major catastrophe happens. It’s often a problem that the sad person feels guilty because they think they shouldn’t waste time being sad when there are children or other life responsibilities involved, but that’s just the opposite. You have to outwardly grieve to get through the change. The new situation has to have a chance to become the new normal. I think the best thing is to not tell someone about all the good things he/she has goin – say “you damn-well ought to feel sad because this sucks.” When I had my worst turn many years ago, I was rescued by music. I met a really great guitar teacher at just the right moment who taught me the blues – the real, old, acoustic finger-style blues from the Mississippi delta that’s hard to find recordings of. Blues music was great because you’re encouraged to explore pain on a visceral level – even literally applauded for how rotten you feel. I just started playing pubs and coffee houses and shouting (musically) at complete strangers. I took my pain and re-organised it into what I wanted it to be; learnt to laugh at my own misfortune and pain because it was mine and I could do with it what I willed.
If you know someone who suffers from depression caused by a situation or event, help the person acknowledge everything he or she is feeling, claim every pain as one’s property in some way, then maybe the person can feel he/she has some power over it.