"An apple a day keeps the doctor away" : Stop eating junk food! You kids are going to end up in a hospital. Remember that an apple a day keeps the doctor away.
If you eat healthy, you won't get sick.
"Alive and kicking" : I heard your grandmother got out of the hospital and she is alive and kicking again.
To be healthy and active despite health problems.
"Feel on the top of the world" : I've been exercising and eating healthy, so now I feel on top of the world.
To feel very well.
"Back on one's feet" : Look at you! Nothing changed after the accident, you look just as healthy as before.
To be well again after health problems.
"Under the weather" : I'm sorry but I can't go, I'm under the weather today and I need to go to the doctor.
To feel sick.
"A taste of your own medicine" : Don't be nice to him, I think he needs a taste of his own medicine to stop treating people so badly.
To pay back to someone who did wrong to teach a lesson.
