'You dont seem depressed'

This has to be the worst thing ever to say to someone who is dealing with depression, just because someone doesn't act depressed or smiles, that there not going through a really hard time, I smile, I laugh, I have good times, but deep inside I'm struggling, I feel isolated, lonely, useless, fed up and want to run away from everything in my life. Stop telling people that they don't look depressed or they can't be depressed because there smiling. You can't tell how a person is feeling deep inside.