Frustrated souls have always complained, in the heat of stress, that something or someone was "driving me crazy." But is it possible to literally go "crazy"--to develop a mental illness--from the effects of emotional pressure? Strictly speaking, mental illness is caused by chemical imbalances in the brain. Like any illness, it can be abetted by genetics or prenatal influences; triggered by outside physical factors; and treated by medication. However, anyone who worries about personally developing mental illness should know three things: Genes are not destiny. Just as with breast cancer or diabetes, mental illness can "run in families." That doesn't mean, however, that everyone whose father and grandmother had schizophrenia is doomed to develop it, even if they have every other physical factor in common. It only means that extra caution is required in avoiding known risk factors. (The "avoid risk factors" principle is especially relevant with illnesses that manifest as alcoholism or other substance abuse disorders; if your family has more than its share of alcoholics, you're well advised to play it safe and avoid even social drinking.) Never "resign" yourself to developing the family problem; that in itself may increase your risk. Chronic stress and physical injury (especially injuries to the head) do correlate with higher incidences of mental illness. Whether or not you know of mental-illness trends in your family, guarding your head mentally and physically will reduce your danger of being found in a high-risk group. To prevent physical injury, wear a helmet for sports and outdoor cycling, and a seat belt in the car. On the mental-emotional level, much stress can be avoided by holding to standards for your jobs and relationships. To minimize the inevitable circumstantial stress, develop early on the habits of good time management; daily relaxation and meditation; and affirming regularly that your own attitude is more controllable than the rest of the world. Actual mental illness does not inevitably destroy all ability to function. Contrary to popular stereotypes, most people with mental illness manage to lead "normal" lives with little or no help. Medical experts now agree that 20 to 25 percent of the population has some level of mental illness, which means that most of them (and their acquaintances) never suspect it, or chalk it up to "just being a bit stressed." Even mild mental illness, however, can grow into serious problems. If you're concerned, check common symptoms (http://psychcentral.com/quizzes/) and make an appointment with your doctor. (You don't necessarily have to find a psychiatrist; your regular GP should be qualified to do screenings, prescriptions, and therapist referrals.) And if you internalize only one thing from this article, make it this: casting blame helps nothing. Instead of feeling sorry for yourself and angry at circumstances, concentrate on your own responsibility to make the best of what you have.