If you lost your teenage years to mental illness and/or trauma, I just want you to know that you did not "miss out on the best years of your life" and that it isn't actually too late for you to have fun, explore yourself and grow into the person you want to be. There's still plenty of time for all of that. I promise.
If you tell someone that what they're going through isn't that bad, don't expect them to keep in contact with you. You are not able to measure someone else's pain and/or tolerance for certain things so don't try and tell them that it isn't that bad or that you've seen worse, because by saying that, you're invalidating their feelings and making them rethink themselves.
It doesn't take much to be kind, so don't be a shithead xx