This question can be replaced to: [Are you sure you can do it?]
This question can be replaced to: [How are you?]
They both mean mental state, but
[настрой] goes from weak to strong
[настроение] goes from bad to good
You can not say he has bad [настрой]
You can say he has strong [настрой]
You can not say he has strong [настроение]
You can say he has good [настроение]
Can we say that [настрой] = [готовность к какой-нибудь (активной) деятельности]?
In someway yes, but [готовность] in Russian mean [readyness] and therefore it is much wider, than [настрой].
[настрой] can be in someway treated as [mental readyness], whereas [готовность] is more wide.
Let's take exam as example.
[готовность к экзамену] means how good you memorized material.
[настрой] means how confident you are, how you are sure in your abitility to pass exam.
[настроение] means general state of your mood, which may be different from [настрой]. You might have a strong [настрой], but your [настроение] can be bad, because your alarm clock failed to ring and you had no time to have breakfast. That is the case of strong [настрой], but bad [настроение].
There are people, who are not ready for exam, but they are sure that everything gonna be ok. Their [настрой] is strong.
There are people, who are ready for exam and study like crazy, but they are not sure that everything gonna be ok and they lack self confience. Their [настрой] is weak.
Usually [настрой] is the source for [настроение].
If you have strong [настрой] than it will make your [настроение] good.
If you have weak [настрой] that might result into bad [настроение].