Failure to FearThat's right: not fear of failure. Failure to fear.
Fear can motivate. Fear can debilitate. Fear of failure can lead to inaction. In the case of system administration, inaction leads to many issues such as increased risk in the form of delayed patch deployments and frustration due to missed opportunities (could have started using those new features).
Instead of fearing failure, try failing to fear. Failure is the BEST way to learn. Do it in a controlled manner, of course (this requires some planning), but get out there and make some mistakes!