Her only care is the safety of her children.

I am anxious about his health.

I'm anxious about his safety.

As time went on, people grew more and more concerned about the matter.

I am concerned for her safety.

I was worried on her account.

I worry about him.

I am anxious about the future.

Your present trouble is on my mind all the time.

It's a worrying matter.

The affair cost me many sleepless nights.

I'm afraid I'm imposing on your hospitality.

I've had a lot on my mind recently and have had trouble falling asleep at night.

Apparently, Tom had a lot on his mind, so I just left him alone.

That's my sole concern.

Tom was worried about his friend.