Actually, people should generally avoid challenging their instincts.

For example, some people are persuaded to avoid carbohydrates. This isn't necessarily beneficial for health.
In fact, even eating less carbs may not be correct, because I personally stick to a low-carb diet, and now my weight has dropped to the point of being somewhat underweight.
For instance, some people are convinced not to get married or have children, which is going against their reproductive instincts, and that can be very painful.
Not to mention those who are convinced to drink their own urine.