The answer is actually NEVER.
People with mental illnesses already feel like they are a burden to their friends, family, and even their community, so please, take it easy on them.
1. Please do NOT tell someone with a Mental Illness that they need to "get over it."
It is common for people with a Mental Illness to feel like they should just be able to just "get over it" but it is impossible. People with depression cannot just "get out of bed". Anxiety sufferers' can't just "calm down". People with PTSD can't just "live in the moment". Cut them some slack and be a little bit easier on them... it could make their day.
2. Try not to judge.
It is hard to explain to someone who has never experienced a mental illness how hard it actually is to handle. Try to put yourself in the other person's shoes before you judge or assume things about them.
3. 1 in 4 people have a Mental Illness, so remind your loved ones they are not alone.
People with a Mental Illness often think they are alone and nobody understands. Be there for them and remind them they aren't alone.
4. If you're not sure how to help, remind someone with a Mental Illness that they are valuable to the world, do NOT shut them out.
The estimated number of deaths by suicide each year is 800,000. A kind word could save someone's life.
5. Have an open mind, and open arms.
It is difficult to see someone suffering from a Mental Illness. Having an open mind is important, and having open arms is even more important. It is okay to not have all the answers, but a hug and someone to listen is always a good thing to have.