This is advice given by people and even more often by articles. But is it true?

Do you think you get less depressed by doing what happy people do?
If you copy the life of a skinny person, will you be skinny?
If you are anxious, can you look at a really calm by nature person and do what they do and be cured?
Can you get more energetic by trying to have the habits and emotions of an energetic person?

If yes... please explain how.

If no, why are we drowned in articles about traits and habits happy, skinny, productive and energetic people have, if we don't get better by trying to adopt them?

Right now I am told to look at people with normal sleep and just copy them for better sleep. Last night I lay in bed for as long as I should have slept, I didn't sleep one second, then I got up and now I am supposed to live my day energetically with no sleep to do the same thing last night. I have attempted this in the past and it landed me in hospital.