Just comes with practice and time. Used to feel like that. After training my brain and doing a bunch of PTs the feeling fades. Also nice to just have some exterior motivation (think about your career and what you're doing this all for!). I promise the exhaustion will fade

Why could B be wrong. I see it is a unreachable conclusion but my thought process was to use the contrapositive: so I did "do not fullfill -> overwhelming evidence of disaster" is this not valid? I can understand it wouldn't work anyways as your friend being happier still would not constitute overwhelming evidence of disaster. But would it be valid for example if it said "a person should not fulfill his duty to tell his friend about the friend's new haircut, because telling the truth would make the friend fall into a deep depression with extemely harmful results". Would that be valid? Or am I just completely misunderstanding contrapositives