Enchiridion Book

Stoicism according to Epictetus, is:
Don't demand that things happen as you wish, but wish that they happen as they do happen, and you will go on well.
and:
If you ever happen to turn your attention to externals, so as to wish to please anyone, be assured that you have ruined your scheme of life.
My favorite quote, maybe because it's so personally relevant and so incisive, is, and bear with Epictetus, this one is a bit long-winded:
In every affair consider what precedes and follows, and then undertake it. Otherwise you will begin with spirit; but not having thought of the consequences, when some of them appear you will shamefully desist. "I would conquer at the Olympic games." But consider what precedes and follows, and then, if it is for your advantage, engage in the affair. You must conform to rules, submit to a diet, refrain from dainties; exercise your body, whether you choose it or not, at a stated hour, in heat and cold; you must drink no cold water, nor sometimes even wine. [...:] When you have evaluated all this, if your inclination still holds, then go to war. Otherwise, take notice, you will behave like children who sometimes play like wrestlers, sometimes gladiators, sometimes blow a trumpet, and sometimes act a tragedy when they have seen and admired these shows. Thus you too will be at one time a wrestler, at another a gladiator, now a philosopher, then an orator; but with your whole soul, nothing at all. Like an ape, you mimic all you see, and one thing after another is sure to please you, but is out of favor as soon as it becomes familiar.
At other times, his advice is a little harder to swallow:
If, for example, you are fond of a specific ceramic cup, remind yourself that it is only ceramic cups in general of which you are fond. Then, if it breaks, you will not be disturbed. If you kiss your child, or your wife, say that you only kiss things which are human, and thus you will not be disturbed if either of them dies.
The overall approach to life reminds me a lot of Eastern philosophy's non-striving which I've found to be practical and beneficial. I think Epictetus captures well the balance between a complete lack of ambition and allowing ambition and materialism to consume you.