Do u think my essay introduction is good?

It depends what grade you're in. If you are in middle school or above, you shouldn't address your reader or mention yourself. No "you"s, "we"s, "I"s, or "me"s. You can just take out the "did you know that" and its fine. As for continuing like that, yes, I think it works well. You might want to explain how stress affects the body. Overall, its a good start.