I take it from this that you have been depressed, and were able to decide not to be, and recovered.
Yes, I went through severe depression off and on for years. Someone I trusted implicitly told me that depression was a choice and I angrily stewed over that for a year. Then one day I snapped to the truth of that and in a few minutes my depression lifted completely. I literally felt it physically lift off of me like a heavy blanket. That was in '96 and I haven't been depressed a single day since. The whole thing became clear as a bell to me.