A person who has not been deeply depressed will NEVER understand unless it happens to them. Combine deep depression with OCD and anxiety and it's a hundred times worse. Just imagine going from feeling "normal" to a feeling of sadness and not knowing why you are so sad. Imagine not being able to get out of bed, laying there with your mind racing so fast that you can't focus on any one thought, your head spinning so fast and you can't make it stop. Imagine going to work everyday so full of sadness and worry that you are on the verge of tears the entire day. There is NO way to convey that feeling to anyone unless they have themselves suffered from deep depression. You could try putting a paper bag over your head and spinning yourself around for 20 minutes while listening to cymbals clanging together rapidly and someone could be throwing rotten tomatoes at your head. That might give you some idea of how it feels to be deeply depressed, but not really because it's much worse than that.