Fine.

The riddle refers to a variety of meanings of the word fine.

Feeling normal refers to when you feel fine.
Extremely thin refers to a fine thread.
A punishment refers to being charged a fee.
The one who wins refers to an athlete who is physically trained and hardened close to the limit of efficiency.
Free from impurity refers to measuring the fineness of precious metals.
A keen edge refers to a knife with a fine edge.
Refined refers to fine manners or elegance.