Three Strikes And You Automate

The first time you do something, you just do it manually.
The second time you do something similar, you wince at the repetition, but you do it anyway.
The third time you do something similar, you automate. AutomationIsOurFriend.

Examples:

The process of renaming a class. When you're using file-based source code and a file-based version control (such as CVS), renaming a single class is an ordeal. Use something like ReadWriteGrep and some ad-hoc scripts to make renaming a class more enjoyable event. (Or use EclipseIde -- or IntelliJ IDEA)
Build dependencies in C++. You really shouldn't have to recalculate these by hand. See the suggestions on RecursiveMakeConsideredHarmful.
ProgrammableDayTrading (and other business automation)
construct a GUI test-free, by running it over and over again, frequently by using the debugger
Don't forget TabCompletion, just because you use it without thinking.
...

ThePowerOfNow may be useful for justifying automation's costs to the PointyHairedBoss. Perhaps I should read it?

This violates the ZeroOneInfinityRule. You should automate on the second step because you KNOW you will repeat it.