Stress... ??

There are a few meanings, but here I want to talk about the noun. Physically, stress is pressure. When you press your thumb and forefinger together, you can feel it. It also means emphasis, special attention for something important.. Okay, enough, now I move on to the main part. Unseen one.

Abstractly, stress is kind of worry, indeed an extreme one, that you feel something press on you when in fact there is none. How does it feel? I don't know.. I wish to know. Will someone please be so kind, to name me an example?
Many people claim that they have stress on studying or working, but, do they really feel stress? how? Or is that simply panic and anxious?
For some people, stress is caused by incomplete love. But to me, all these are but negative thinking. Saying how you cope with stress shows no confident, complaining that you are stressed shows not giving enough effort. How can you give up when not even have tried? Perhaps, if stress really occurs on some individuals, those are with mental illness.

Positive minded attitude(PMA). I saw this once, but forgot the source. The conveyed meaning is so deep... We shall at least practise it always. Mind this, when you think positively, you won't know what stress is.

Recently I met someone, an interesting one, "... you might not believe, I am crying..." I asked why, and she said the song was sad, so she cried. I did believe her, and somehow salute. Is it that easy to cry? This is definitely not an expression of stress, or?