気にする (mind, worry about)

She acted as if she didn't care in the slightest about what had happened.

You don't need to worry about what that fortune-teller said yesterday.

She doesn't care about other people. In other words, she's self-centered.

She is self-conscious about her looks.

She was very worried about it.

She doesn't care in the slightest about her test score.

I was worried about not having sent a reply.

She doesn't mind in the slightest.

She's deeply concerned about the result.