Hi, kib. USE SHORT SENTENCES! Keep this upper-most in mind. It really works. It is very useful to prevent mistakes. It makes compositions much more comprehensible and easy to read.

Your first paragraph:

People are said to be leading very stressful lives nowadays. Probably, That's true - life has become so complicated, so diverse that much more the problems come out that people have to face, to solve than ever. It's like being very rich - you have a more chance of being robbed than an average person. Some people can't bear it any more, they give in, and their health and even their lives are in danger, because we know, what a stress can lead to. But I think you agree with me that people don't put up with it - they fight with it; why do you think psychologists of any kind are becoming more and more needed, why do you think there is a great lot of humorous programmes and entertainments? That is very wise of humanity to use them against stress, and popularity of the things proves that they are of good use.

A simple edit job, to make shorter sentences:

People are said to be leading very stressful lives nowadays. Probably, that's true. Life has become very complicated. This diversity means many more problems arise that people have to face and solve than ever before. It's like being very rich. You have more chance of being robbed than an average person. Some people can't bear it any more. They give in. Their health and even their lives are in danger. We know this because of what stress can lead to. Perhaps you would agree with me that people don't put up with it. They fight with it. Why do you think psychologists of all kinds are becoming more and more needed? Why do you think there are so many humorous programmes and entertainments? It is very wise of humanity to use them against stress. The popularity of these things proves that they are of good use.

I have tried to edit structure and a few wordings, not sense, nor ideas, nor other style points.


"One more thing.
There was nothing to do but leave. I'm curious to know: what член предложения (subject, object and so on) is leave here?" 'Leave' is a verb in that sentence.