I need to find a/an verb/idiom/expression to describe the situation that someone suddenly becomes too disappointed/cold in doing something they had planned to do.
Formerly, perhaps because of the word "cold", I used to utilize the idiom "get cold feet", but later, I found out that aside from the fact that most of the times, it is used for an important mater especially getting married, it alludes to an occasion in which someone is frightened to do something, (not only getting cold/disappointed).
Well, please assume "young" boy who feels really down after a failure in his university entrance exam for the second time and now he's severely suffering from the situation he's in.
- Son: I failed the job entrance exam. I have to wait for another one whole year. I cannot even think about that for a second! That's a catastrophe.
- Dad: Be hopeful Jerry! You're my Son! Not only now, but you should never get cold feet.
I apologize if my dialogue does not sound that idiomatic to you! It was just a made-up scenario to convey the message in my question.
I wonder if the idiom "get cold feet" works in the above self-made case? If not, what would you say instead?
I doubt if the verb "get cold in something" works!