Depression?

OK, so at work the other day I was asked by a co-worker if I've hit the depression stage yet? He said his son had bariatric surgery and he's in a deep depression because he's at a point where he has realized that he cannot be "normal" anymore. I have never heard of this "stage" before and I was curious as to whether it was real or not? I believe that this is something that is possible BUT I also know what I've put myself through by getting this surgery but I know that I will have a new "normal." I felt like this co-worker was trying to set me up for what his son went through. I told him that with each day, I get happier and happier with my progress and I don't see where I can get into a deep depression.