Negative Thoughts

I often have (what feel like intrusive) very negative thoughts about terrible, horrific things that could possibly happen to me. It’s usually one to two things my brain is focused on and just keeps repeating; like it’s obsessed with convincing me these things are going to happen! It’s scary, frustrating and tiring.

When I catch my thoughts, what could I say to myself to redirect my thinking to something more neutral / positive? Thank you.