It's hard to remember that we aren't always in control. But that's just the way it is. 

Here is the quote:

“The cucumber is bitter? Then throw it out.

There are brambles in the path? Then go around them.

That’s all you need to know. Nothing more. Don’t demand to know ‘why such things exist.’ Anyone who understands the world will laugh at you, just as a carpenter would if you seemed shocked at finding sawdust in his workshop, or a shoemaker at scraps of leather left over from work” 

- Meditations, Book 8