There seems to be a belief in modern society that one has to be happy all of the time. I'm not sure where or when that started, but I don't think it's a natural state for humans to be happy all the time. Sad things happen in life and part of being able to deal with it and let go is feeling the sadness. I also think we wouldn't appreicate the good times nearly as much if we were happy all the time. But we've been sold the idea of happiness looking a certain way and we've been sold on the idea that if you're not happy all the time there is something "wrong"--something needing to be fixed.
Do I think there are genuine times when people need some chemical intervention? Yes. But I think we've oversimplified the solution to bringing ourselves out of the depths. I've been seriously depressed several times in my life and have gotten through them. My latest one was three years ago. I was sitting on my couch sobbing, and I thought to myself "I'd rather die than be in this much pain." It was a scary wake-up call for me. I had never before considered death as an option. I realized something had to be done. I got into therapy, I started making changes in my life and slowly, gradually, I started to feel better. Today, I'm the most content and self-aware as I've ever been in my life.
"I am still determined to be cheerful and happy, in whatever situation I may be; for I have also learned from experience that the greater part of our happiness or misery depends upon our dispositions, and not upon our circumstances."
- Martha Washington