Seneca says:

If you wish to put off all worry, assume that what you fear may happen is certainly going to happen.

I will despise whatever lies in the domain of Fortune, but if a choice is offerred, I will choose the better half.

The wise man can lose nothing. He has everything invested in himself.

The wise man is self-sufficient ... if he loses a hand through disease or war, or if some accidents pupts out one or bothof his eyes, he will be satisfied with what is left.

The wise man is self-sufficient in that he can do without friends, not that he desires to do without them.

Never did I trust Fortune, even when she seemed to be offering peace. All those blessings which she kindly bestowed on me - money, public office, influence - I relegated to a place from which she could take them back without distrubing me. Between them and me, I have kept a wide gap, and so she has merely taken them, not torn them from me.

The one alleviation for overwhelming eveils is to endure and bow to necessity.

... And we cannot change this order of things ... it is to this law [of Nature] thatour souls must adjust themselves, this they should follow, this they should obey ... That which you cannot reform, it is bet to endure.

A Senecanpraemeditatio
[The wise] will start each day with the tought ...
Fortune gives us nothing which we can really own
Nothing, whether publicor private, is stable; the destinies of men, no less than those of cities, are in a whirl.
Whatever structure has been reared by a long sequence of years, at the cost of great toil and through the great kindness of the gods, is scattered and dispersed in a single day. No, he who has said 'a day' has granted too long a postponement to swift misfortuen; an hour, an instant of time, suffices for the overthrow of empires.
How often have cities in Asia, how foten in Achaia, been laid low by a single shock of earthquake? How many towns in Syria, how many in Macedonia, have been swallowed up? How often has this kind of devastation laid Cyprus in ruins?
We live in the middle of things which have all been destined to die.
Mortal have you been born, to mortals have you given birth.
Reckon on everything, expect everything.