I think "Be Content" is a good rule. Be content with where you are and what you have.
I'm not saying don't strive for more but don't make it become an obsession.
Contentment and patience are important to prevent rash decisions that end up bad..
Don't let the world fool you by luring you with pretty shiny trinkets that other people have or by selling you things you "should" have or absolutely "need" when you really don't.
Success comes in many forms and if someone isn't happy and satisfied with their life, they will never feel successful no matter how much they have.
So be content while you dream.
And along the same lines (since I saw it recently and it was in my mind)