Grit!

Grit defined ...

Noun: ​ Courage and resolve; strength of character.

Verb:  Clench (the teeth), especially in order to keep one's resolve when faced with an unpleasant or painful duty.

Resolve defined ...

Noun:   Firm determination to do something. 

Courage defined ...

Noun:   Strength in the face of pain or grief.

Quitting defined ...

Noun:  To give up or resign; stop, cease and discontinue; to stop trying, struggling, or the like;  accept or acknowledge defeat.  

Courage defined ...

Noun:   Strength in the face of pain or grief.

Resolve defined ...

Noun:   Firm determination to do something. 

Grit defined ...

Noun: ​ Courage and resolve; strength of character.

Verb:  Clench (the teeth), especially in order to keep one's resolve when faced with an unpleasant or painful duty.