“Aim to please”
I think that might become my motto. After all it is a very prevalent part of my personality.
I’ve had the same motto for several years. I know I got it from somewhere, but I don’t remember where:
Eat when you’re hungry. Sleep when you’re tired. And scratch where it itches.
Not real deep, I grant you, but it works for me. I guess it really boils down to “Listen to your body”. If I’m not hungry at “lunchtime”, that’s OK. I don’t have to eat just because other people are. The sleeping part is more difficult, since employers generally have an expectation of when you’re going to come in to work that doesn’t vary too much from day to day. And the scratching part should be self-explanatory. 
Oh, and then there’s “Life is too short to drink bad beer”.
Nice motto, except I’m always hungry, never tired, and scratching makes me itch.
Well then, you should be eating all the time, and never sleeping or scratching. That’s what’s great about my motto; it can apply to everyone.
Hey, cool – someone who doesn’t think I’m cracked out.
What?
“Don’t take any guff from these swine!” - Hunter S. Thompson
I’ll leave it up to the reader to decide if the man did, in the end, take guff from these swine or not.
Not officially, but cum grano salis sums things up pretty well.
“Que sera, sera” is a good one. I’ve always translated that as “What will be, will be.” I use that one when I’m in danger of worrying overmuch about anything.
Not a single motto, per se, but I like to follow the philosophy of Grandpa Vanderhoof in “You Can’t Take It With You.” This is the man who walked out of his office building one day to go raise snakes, doesn’t “believe” in income taxes (heck, ends up faking his own death to get out of them), and addresses God, “Well, sir, here we are again…”
Sans peur, sans honte.
Without fear, without shame. It’s been mine for 25 years or so. Thanks for asking.
Any number came to mind, but I think this one is the most helpful today.
“Don’t stick your hand in the crazy.”
Words I try to live by.
Get busy living or get busy dying.
I made that one up. Yep. All by myself.
I love the film you were watching while you made that up. It’s one of my favourites. 
I didn’t do it.
or
It wasn’t me.
Depending on what kind of mood I am in.
For motivation
“You are the sum of your actions”, which is wrapped in several layers of Existentialism and Sartre of which I understand little. It has also been abused to the point of appearing in business motivation talks. But I still can’t think of anything else which motivates me better, so I guess it’s the closest I have to a motto.
For life in general:
“Etcetera”, as a shorthand for “Life goes on”, “Que sera sera”, “And so forth”, etc.
“Always…no…never, forget to check your references.”
I think the young people enjoy it when I “get down” verbally.
Seriously, my grandfather used to have three pieces of advice:
[ol]
[li]Never sit with your back to the door.[/li][li]Never enter a room with only one exit.[/li][li]Never come out the way you went in.[/li][/ol]
Paranoid? A bit. But remember, even paranoids have enemies.
Stranger
“Whatever.”
That’s my motto.
“Everything in moderation. Including moderation.” - from my great-grandmother, who firmly believed that going overboard sometimes was necessary for good mental health, but not advisable as a way of life.
My husband is a chronic worrywart, always figuring the worst-case scenario. My idea of putting things in perspective for him is, “And you COULD get run over by a trolleybus,” which is family shorthand for “You can’t be prepared for everything, and while you’re worrying about the future, you’re missing the present. You could be dead tomorrow, and none of this worry will matter to you. Live NOW.”
I know I have already posted, so in continuation with that I would like for you to know that I have adopted “treat everyone you meet like they will die at midnight” as a personal motto. Prior to that post, I had always thought along the same lines, just could never phrase it right.
My other motto is ‘Live forever – Or die trying!’
I was at Fred Meyer last week to return a can of spray paint that wouldn’t spray. I was in a hurry, and there was an elderly woman (I think I heard her say she was 90) in front of me. I was getting a little ticked, because she was so slow and the nature of her exchange required sending someone out from the garden department. Then I remembered those words from the guy at the seminar. After that, it didn’t seem like much of a wait.