One of my favourite sayings is “It is easier to ask for forgiveness than to get permission”. This is something I say to myself when I find myself in a state of inertia, often when worrying about doing something new.
The source of this quote was Grace Hopper, a Rear Admiral in the US Navy. She was among the first computer programmers, wrote the first ever compiler, came up with the term debugging, and a whole lot of other computing firsts. In 1969 she was awarded the inaugural Computer Sciences Man (sic) of the Year award, and lots of awards subsequently. Her Wikipedia entry is an impressive read.
Now as well as a powerful quote, I know about a powerful woman to inspire me to be just a tad more adventurous.