I am not going to pull a quote from the article below because what Naomi has written should be read in its entirety.
It’s not just saying I believe you when someone tells you they are struggling with depression or anxiety. It’s all of the subtle ways we show them that we don’t believe them. The “But you don’t look”, the “you’ll be fine”, the toxic positivity, the refusal to change your own behavior in supportive ways, etc., do just as much damage. They send the message that we don’t believe what you just said is serious enough to warrant doing anything differently.
Is that the message you want to send someone who trusted you enough to admit they are struggling with you? That their struggles aren’t valid enough for you to do anything differently?
Like I said, go read the whole thing and think about how we respond to people who share their feelings with us and what we could do instead.