Don't let (something) get to you.

If something bothers you, worries you, frustrates you, angers you, and so on, then you can also say that it "gets to you".

"Don't let ___ get to you" is a common piece of advice. It means that you shouldn't get too upset. Tell your friends or family members this when they have some kind of problem and seem to be in a bad mood about it.

(someone's) pettiness

A person who is "petty" is mean to other people for small and unimportant reasons. Here are some examples of "petty" behavior:

• a teacher gives a student a failing grade on a test because the student wrote it in ink instead of pencil
• one of your children complains because his brother got a slightly larger piece of cake than he did
• a neighbor calls the police to complain about the volume when you listen to music on a weekend afternoon

"Pettiness" is the noun form of "petty". Use "pettiness" when you want to comment on this quality:

Pettiness is one of the least attractive qualities a man can have.

I'm tired of his pettiness and jealousy.

(someone's) negativity

"Negativity" is the quality of someone who criticizes things too much, acts suspicious of people, gets depressed easily, and so on. In other words, "negativity" is bad emotions.

"Negativity" is a noun that's based on the adjective "negative", so you use it like this:

Don't let that kind of negativity into your life.

Negativity spreads like a disease.

I've had enough of your negativity!