Alive and kicking
In good health despite health problems
- Tom is old but still alive and kicking!
As pale as a ghost
- He turned as pale as a ghost when he saw his injured leg.
At death’s door
Very near death
- A.I.G., the world’s most famous insurer, was at death’s door.
Back on one’s feet
Physically healthy again
- "We'll soon have you back on your feet again," said the nurse.
Feel on top of the world
To feel very healthy
- The sea and the warm sun made us feel on top of the world.
Go under the knife
- Kelly was about to go under the knife when her surgeon stopped everything.
Green around the gills
To look sick
- Some of the passengers looked kind of green around the gills after the trip!
Sick as a dog
- I was sick as a dog after last night's meal.
Under the weather
Not feeling well
- I'm feeling a bit under the weather - I think I'm getting a cold.