Let them borrow your calm. Little ones (grownups too) sometimes just need to freak out a bit. Stay there. Be near. Don’t judge or even help. Just be there, and stay calm. Your loving energy is all they need as they work through it themselves. Keep them safe but other than that don’t help or advise unless they ask.
Consider the source.
When you get information, look at where or who it’s coming from. Do you trust them? Are they an expert?
When someone criticizes you. Do they know why they’re talking about and are they taking chances themselves. Pay no attention to hecklers.
I’ve stopped worrying about you being able to make your way through life. You’re not even 8 years old and I can see you’re going to be just fine. You’re smart, kind, curious, hilarious and so very lovable. I worry about your safety, I stress about your health, but I don’t worry about your character. I’m so proud of you, and I love watching you grow.
Trust me when I tell you that one day you’ll look back and realize you judged people unfairly and you held strong to convictions only to end up changing your mind about in the light of life experience. Leave a little space open for second impressions or the possibility that you could be wrong.
On grief: CS Lewis said somewhere that it isn’t just that his friend died, it’s that the part of him that only his friend could bring out would never be brought out again.
Talk about how choices become habits. Habits can become addictions. Describe how pathways are literally dug into the brain and it's very hard to change them once those paths are made.
Look into a class for meditation for kids. I read an article on a Baltimore elementary school that replaced detention with meditation and had amazing success.