An apple a day keeps the doctor away
Eating healthy foods will keep one from getting sick (and needing to see a doctor)
Alive And Kicking
In good health despite health problems
As pale as a ghost
Extremely pale, white skin like a ghost (very sick or scared)
Under the weather
Not feeling well
At death’s door
Very near death
Back on one’s feet
Physically healthy again
Black-and-blue
Bruised, showing signs of having been physically harmed
Catch one’s death of cold
To become very ill (with a cold/flu etc.)
Bitter pill to swallow
An unpleasant fact that one must accept
Feel on top of the world
To feel very healthy or good
Go Under the Knife
to have surgery
Sick as a Dog
Extremely ill
Taste of your own medicine
The same unpleasant experience or treatment that you have given to others
Just what the doctor ordered
Exactly the thing that is or was needed to help improve something or make one feel better
Laughter is the best medicine
Laughing a lot is a very effective means of recovering from physical or mental injury
Run in the family
To be a common family characteristic