Don't demand that things happen as you wish, but wish that they happen as they do happen, and you will go on well.

...

If you want to improve, reject such reasonings as these: "If I neglect my affairs, I'll have no income; if I don't correct my servant, he will be bad." For it is better to die with hunger, exempt from grief and fear, than to live in affluence with perturbation; and it is better your servant should be bad, than you unhappy.

...

Remember that you must behave in life as at a dinner party. Is anything brought around to you? Put out your hand and take your share with moderation. Does it pass by you? Don't stop it. Is it not yet come? Don't stretch your desire towards it, but wait till it reaches you. Do this with regard to children, to a wife, to public posts, to riches, and you will eventually be a worthy partner of the feasts of the gods.

http://classics.mit.edu/Epictetus/epicench.html