Never fear things you can't prevent because there is nothing you can do to change them.
Only focus on things you can change, or the effort you put into life.
That alone will alleviate much anxiety.
Why would I fear cancer if there is nothing I can do (smoking aside) to prevent my cells from going wild?
I can't control the actions of a crazy person...why fear the threat?
We're all gonna die. You can only influence when it occurs, within reason. But don't fear death other than making yourself ready for it's outcome ... whatever that means to you.