Psychological stress is the brain's state in a situation where the cost of "taking it easy" is high.
A few examples.
Driving in heavy chaotic traffic is stressful (the cost of taking it easy is accident and death), preparing for an exam is stressful (the cost of taking it easy is professional and social disgrace), taking care of a child in a war-zone is stressful (the cost of taking it easy is to lose a life), keeping one's job in a time of recession is stressful (the cost of taking it easy is bankruptcy), ensuring one's credit report is clean is stressful (the cost of taking it easy is not being able to buy a car or a house in the future), listening to one's resentful spouse is stressful (the cost of taking it easy is escalation of conflict, separation and potentially divorce), living in a crowded metro is stressful (the cost of taking it easy is not being able to get anything done).
Stress is also there when a situation is felt to be out of one's control. One feels less stressed if one feels capable of solving a problem on one's own. A toilet failing (or the non-arrival of the maid/babysitter) in a modern home is a rather stressful situation.
Stress is not just because the individual is fearful, cautious, apprehensive, greedy, ambitious or insecure. The situation may very well deserve a heightened-attention response. Some people are less stressed about the same event. Once again, that may be due to the individual's affective make-up, as well as his preparedness for the worst outcome. For example, a man with a savings worth a few years' salary will be less stressed about losing his job than one who has no savings and is living on credit. And a man who has no family to support may be less stressed about news of corruption in health-care than one who has asthmatic kids and a diabetic wife.
Modern urban and white-collar life is psychologically stressful despite all the comforts and institutional support mechanisms because of the ... comforts and institutional support mechanisms. Let me explain. If you live in a big city, you need to spend a not insignificant amount of money to have decent housing, you need to have more possessions (e.g. a vehicle, telephone) than a villager because you will be otherwise handicapped and require special and discretionary treatment. I have a friend who refuses to learn driving. It is a good thing he is rich and has a driver. Others who are as stubborn might have to sweat it out in the grimy buses and with rude auto-wallahs.
Most of the so-called comforts of city life are almost necessities. Yes, having them means one can go to a multiplex and sleep in a cool room. But not having them in the city is worse than not having them in a village where they are not needed to fulfill the basic needs. I cannot stress this enough.
Similarly, institutional support (roads, traffic, police, ambulances, hospitals, fire brigades) is a necessity in a large city. But institutions mean that you delegate some very crucial aspects of your life to others. You depend on others in a significant way, and hence maintaining the quality of those institutions becomes a stressful concern.
Most of all, however, the institution of money is what I think leads to an unavoidable situation of stress. Money is a contract about future interactions in which the terms of the contract (inflation, purchasing power, interest rates, duties/taxes, bank solvency) are mostly controlled by others. This leads to a peculiar feeling that no amount of money is ever enough. Without money, you can't move an inch in a modern civilization (and exceptions are therefore remarkable). Money is an institution which one can't do without, and which is to a frightening degree out of one's control. Hence, stress.
It is easy to comprehend that to reduce one's commitments and engagements is a way to reduce stress. The less one has to engage with others, the less the things which are dependent on oneself, the less dependent one is on others, and the less one is affected by changes in circumstances.
It is also easy to comprehend that to manage similar levels of stress better (for example, some stock traders sleep better than others) is a useful skill. Some people are able to "handle" stress better and though some of it may be due to their constitution, better responses to stressful situations can certainly be cultivated through various practices.
Stress is a psychological response to a challenging situation. If one is bothered by the mental state in a situation of stress, one either works at the psychological response, or at the situation.
People differ in the mechanisms they can muster to cope with stressful situations. Since these are volatile times of rapid change, some people can choose to drop out (to various extents) from the flux and flow of society. They may want to live in a village, or in a commune, or live as a retired person, etc.
Others can adapt various dissociative techniques, denials, paradigms and psychological postures to inure themselves from feeling stressed. A possible psychological posture may be to say "So What?" to a situation of stress (not that I recommend this posture). Others may find solace in prayer and community.
Given that each person differs in their affective make-up, inclination, intellectual capacities, and in their circumstances, there is no one-size-fits-all coping solution. Some may be more inclined to religion, some to books, some to traveling, some to remaining bachelors or spinsters, some who are highly capable of handling stress may become entrepreneurs, some may take to crime, some may want to effect a "radical mutation in their brain", and so on and so forth.
And the important thing to me seems to be: Unless one's coping mechanism introduces even more stress in others than it reduces in oneself, generally one should be left alone with one's devices.
If a fringe guru/ideologue is advocating some arcane spiritual/social remedy and if people are gathering around him feeling interested, no need to fret. To each his own. It is when they force others to adapt their beloved remedy that things get ugly.