What is your one guiding principle?

You really only need one.. It is your personal mission/vision/values statement and all that you do and act on must align with it.

Mine:

What we do in life echoes in eternity

It doesn't matter who you are, what you do, how much or how little money you have or make or made.

It's never too late to find something and live by it.

It doesn't matter if they are your own words or not.

Chances are you always knew what that one guiding principle was all along but could never put it into words, or there weren't words that you could find that would describe that principle.