In certain sectors of society, saying "most Americans don't understand ... You're part of a generation which has, by and large, become ... at our own levels of knowledge about mental health disorders and see what's lacking
Answer:
Is there any context to this? Is there a short story or smary before the question?
A warmup is to prepare gently before a physical performance. A cool down is to do exercise at a lower intensity. They are similar because you can do the same thing for each, such as doing a few stretches, jogging a lap or two, maybe even taking a few deep breaths.
I would say hair, since puberty is when young teens start shaving their armpit and leg hair.