I was reading a friend's blog ( http://www.our-journey-through-life.com/ ) and she was addressing the issue of people saying "Just snap out of it" to those with a mental illness. I have personally experienced this. I was told when I had PPD that I needed to just decide to "stop wallowing" and make up my mind to overcome it and just start praising the Lord. This is essentially the same thing, only couched in Christian-ese. Yeah, because I WANTED to be miserable, have to take medication, be a hormonal/emotional mess, never know what would set me off crying, and not fully enjoy my husband, daughter, friends, church, pets, and every day life. I really actually preferred to go through life in a haze of darkness instead of making that simple choice to just start praising God or just snap out of it or just make up my mind to be happy or whatever.
I think that for anyone who has never experienced first-hand what it's like to live with a mental illness/emotional health problems/whatever you want to call it, it's pretty much impossible to understand what it's like. It's easy to roll your eyes and say "Oh whatever, they're just having a pity party. Why can't they just make up their mind to get over it?" but it's really not that easy. Not with a legitimate issue. It can actually be damaging to have someone tell you that. When you say that to someone, do you realize that you are essentially saying that they are lying? Do you realize how hurtful that can be to someone who is already in a fragile place?
Next time you want to just roll your eyes and dismiss someone's issue and say "Well if you're not happy then just make up your mind to cheer up" or something of that type, stop and think about whether that is really a helpful thing to say. Consider that if it really were that easy, they probably would already have done it.