Someone could certainly give you a thesis statement and 3 topics for this paper - but then the paper wouldn't really be YOURS. You need to own it. The best way to do this is to draw these things from what you already know.
An easy way to come up with a thesis statement (and material for an entire paper, really) is to follow these steps first:
- State the topic in the form of a question. What are the effects of stress on health and behavior?
- Brainstorm a list of 15 - 20 answers for the topic question. Be as general or specific here as possible - remember it is just brainstorming so no ideas should be ruled out. Also, keep in mind both negative and positive effects of stress.
- Categorize answers into three logical groups. Do not make two of your categories the "negative" effects and the "positive" effects. Instead, focus on one or the other. Otherwise your final paper risks a lack of cohesiveness.
- Write thesis statement by giving a general and complete sentence answer to the topic sentence. While stress has both positive and negative effects on health and behavior, the negative tend to outweigh the positive.
Then, your next sentence is blends naturally into identifying your three categories (major points). Hope this helps.