If I eat an apple, I'll stay well
Go under the knife
To have surgery
To bite one's tongue
To make a desperate effort to avoid saying something
To give someone a hand
To help someone
To go toe to toe with someone
To stand in competition with someone (literally or figuratively) in a forceful determined way
Laughter is the best medicine
Laughter is good for us all/promotes good health, etc.
Snake oil
Something presented as a 'cure-all' but that's really not true (like old-timey elixirs)
To stick your foot in your mouth
To embarrass yourself
Butter fingers
Clumsy, someone who drops things or let's things slip out of his/her hands
In over my head
In too deep; no longer able to make wise decision in the matter/situation out of control
Alive and kicking
Feeling well
Sick as a dog
To feel just awful
To get cold feet
To become scared (i.e. getting cold feet before marriage)
Two left feet
Someone who is clumsy i.e. can't dance
Face the music
To take responsibility
Fit as a fiddle
To be in good health (often to refer to a health senior)
Pale as a ghost
To look sickly
To hurt someone's feelings (often in love)
To stab someone in the back
To betray someone
To walk on eggshells
Tread lightly around someone based on their bad mood
Under the weather
To feel sick (but not too sick)
To be on the mend
To be getting better/recovering from an illness or injury
Heart of gold
Someone who is well meaning, kind, an overall good person
To go behind someone's back
Eyes in the back of your head