After reviewing the provided sources, there is no information regarding a discussion between yoga instructors and their students about Lipitor. Lipitor is a prescription medication used to lower cholesterol levels, and it is important to consult with a healthcare provider before taking any medication, including Lipitor [1].

The sources do discuss the potential risks of practicing too much yoga. While yoga can be beneficial for overall health and well-being, overdoing it can lead to injuries, particularly if the poses are not done correctly or if the body is pushed beyond its limits [2]. Pregnant women should also be cautious when practicing yoga, as certain poses can be harmful to the developing fetus [3].

In conclusion, there is no information in the provided sources regarding a discussion between yoga instructors and their students about Lipitor. However, it is important to consult with a healthcare provider before taking any medication, including Lipitor. Additionally, practicing yoga can be beneficial for overall health and well-being, but it is important to be cautious and not overdo it, particularly if you are pregnant.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://www.everydayhealth.com/yoga/are-you-doing-too-much-yoga-heres-how-to-tell-and-why-it-can-be-risky/
[3] https://www.reuters.com/article/us-fitness-yoga-prenatal/prenatal-yoga-pregnant-poses-great-expectations-idINTRE5B62SE20091207