Learn English – polite, formal way to say “sh!t happens”

politenessslang

I am trying to write an essay and the only phrase I can think of is "shit happens". I'm wondering; is there any formal way to say shit happens?

I think the closest expression with the same meaning and very similar connotations would be the French expression:

C'est la vie.

meaning

That's life.

You can use the French phrase as is because it is famous enough to be understood in any English speaking country.

Certainly there are some more possibilities to say it in a polite way as to avoid vulgarity:

Stuff happens.

or you can use the English idiom:

Worse things happen at sea.

as a way of telling someone not to worry so much about their problems.