Fear is often a good thing. It makes us think twice. Ideally it can reduce mistakes.
But handled the wrong way, fear can backfire, it can be self-fulfilling.
For example, let's say you're afraid of upgrading your software. That's understandable - software upgrades can be painful.
But how you handle the fear is important. It's positive if it encourages you to be cautious, to test the upgrade first, to upgrade in a way you can rollback, to upgrade at a slow time when you'll have time to recover from any problems, to wait for version 2.1 instead of 2.0
Instead, you might let your fear stop you from upgrading. In the short term this saves you work and pain. But in the long term, you're going to have a problem. The longer you go without upgrading, the scarier it gets. Before you know it you're three versions behind and your version is no longer supported. Now you are forced to upgrade, and now you're pretty much guaranteed to have problems.
Or lets say you're afraid of your server crashing because you're not sure you know enough to re-install and re-configure it. Yikes! That's cause for fear. But the answer is not to cross your fingers. The answer is to solve the problem - get a spare machine, learn how to re-install and re-configure. Do a test run - pretend your server has crashed and go about re-building it.
Face your fears, use them, don't avoid them (or ignore them).
(Note: I'm not saying you should rush to do upgrades - that's just an example.)