Your knee often hurts because of a sports injury you got many years ago. Today it's hurting. Someone asks if something is wrong, so you explain what's happening.
My knee is acting up again.
health, idiom, pain, progressive aspect 
You're having dinner with your family. Suddenly your chest starts to hurt. You're worried about it. Someone asks you what's wrong, so you say:
I'm having chest pains.
body, emergency, health, pain, progressive aspect 
You're talking with a coworker at lunch. She complains that she's tired of sitting in front of her computer all day. This reminds you of something you read on the Internet. You say:
I came across an article the other day about how sitting for long periods is supposedly horrible for your health.
One of your employees looks sick. You ask her why she came to work, and she says that she has a lot of work to do. You'd rather she go home so that she doesn't make other people sick. You say:
If you're feeling under the weather, by all means go home and get some rest.
Your company gives employees free shots to protect against getting the flu. You think everyone should get one so that they don't get sick. In a meeting, you announce:
I urge everyone to take advantage of the free flu shots being offered this week.
advice, formal, health, idioms, infinitive 
Your grandmother passed away after being sick for several years. You’re back at work now after going to her funeral, and talking to a coworker who’s come to give her condolences. You explain that your grandmother's death was not surprising:
Her health had been deteriorating for many years.
You quit smoking a few months ago, and you're really happy not to be a smoker any more. You're talking to a friend who's not a smoker about how bad smoking is. You say:
It's a nasty habit — bad for your health, expensive, not to mention the odor.
Your baby is sick. You took his temperature, and it's higher than it should be; he has a fever. You call a doctor, and explain the problem:
My infant is running a fever of a hundred and two.
baby, children (topic), health, numbers, progressive aspect 
You're chatting with a friend in a cafe. You start to talk about your glasses. Your friend asks how well you can see without them. You take off your glasses and say:
Everything is really blurry. I can't even make out what that sign over there says.
adjective, adverb, be able to, health, intensifier, phrasal verb, vision 
You're about to watch a basketball game on TV. There's a show before the game where the sports announcers discuss the game. They're talking about one of the players who suffered a knee injury last year. One of them says:
The question is whether his leg is fully recovered.
