There have been plenty of studies on the link between stress and its effects on overall health and wellness, so you should be able to find plenty of solid information that supports the effects of stress on a person's health. You may certainly come up with an argumentative thesis statement that claims the link between stress and poorer health is false or exaggerated; however, I think that you will find that argument difficult to support.

My recommendation for the initial thesis is to stay somewhat broad. For example, a broad thesis may read "Although stress is a normal body response to various situations, constant stress can have detrimental impacts on a person's overall health and wellness."

This particular thesis gives you the opportunity to explore what stress is and explain that stress is a normal biological response to certain environmental conditions. Constant and pervading stress is the problem. Your paper should explore that difference.

The thesis provided also stays broad in that it says that stress is bad for overall health and wellness rather than providing specific health problems. This gives your paper room to explore a variety of health complications related to stress. I would spend time explaining that a person's overall health is a combination of physical health, mental or emotional health, and social health. Stress can impact all three aspects of that health triangle, which is your link to how stress can affect behavior.

Definitely explore how stress can contribute to headaches, increased blood pressure, muscle tension and pain, fatigue, and other physical ailments. Discuss how many of these things are also psychosomatic symptoms. The doctor can treat the muscle pain but if the root cause is stress the treatment isn't targeting the problem.

You can explore how stress could lead to mood disorders like anxiety, and those kinds of mental and emotional changes generally impact a person's social health. If the stress leads to frequent bursts of anger, a person might find that their friends are less willing to be social with that person.

Before bringing the paper to a close, I recommend offering your reader some solutions regarding stress and stress management. Explore how something as simple as changes to diet and exercise can lower stress levels.

The previous answer gives a great starting point for how to write any essay of this kind. It is always better to do your research first, and then come up with your thesis statement from what you have found. Trying to summon a thesis statement before you have found your three major points is very difficult and means you risk trying to make the evidence fit the statement, rather than the other way around.

Let's consider some examples of topics you might cover:

The question asks about the effects of stress on your health and behavior, so a good starting point is to recognize that health and behavior are two separate things. We may even be able to break that down further: health could mean physical health and mental health. As such, our three topics might be . . .

1. The effects of stress on physical health

2. The effects of stress on mental health

3. The effects of stress on a person's behavior

So, effects on physical health might include headaches, difficulty sleeping, tiredness, and so on. Effects on mental health could include depression or anxiety, difficulty focusing, and lack of motivation. However, remember that everyone is different—for some people, stress can lead to increased drive. You should always consider alternative viewpoints in any essay. This element could fall under the effects of stress on a person's behavior. Negative behavioral effects might include substance abuse or irritable behavior.

Your thesis, then, should be drawn from what you have written under your three headings. Based on what I have brainstormed above, my thesis might be: "Stress has generally negative effects upon the physical and mental health of most people, resulting in negative behavioral changes." However, your own thesis might be different, depending upon the conclusions you draw and evidence you find.