Jumping off cliffs

Of course it is a metaphor, but I really need to learn to stop jumping off the cliff when something seemingly minor comes along.
I tend to have a very low tolerance for a few things and when they occur I always head straight for worst possible scenario. And it really does the head in sometimes.
It doesn't help being your own worst enemy when it comes to your mental health, let alone physical. I've found that when the first suffers then the second suffers but, more alarmingly, it is when the second suffers first that it really hits the first. If you follow that logic.
Gotta change.....