I highly recommend Dr. Mark's "How to Optimize Your Immune Health" Course. I really enjoy this interactive course and feel very fortunate to take it. Before I took this course, I have had years of fatigue, discomfort over my body, poor sleeping quality, mood swings, and a lot of other problems such as easy to catch a cold. Over the years, I accumulated a lot of stress although I lived very carefully. I watched my diet carefully and maintained a very careful lifestyle. I was in different clinician's offices for years. And yet my problems were never solved, and my symptoms were hardly improved. After taking this course, I started to learn that surprisingly these seemingly unrelated problems are intertwined with each other and share the same root-cause. Dr. Mark has laid out a good foundation in this course and explained well to us why our immune system got weakened and problems start to occur. After I followed the instructions from this course and took action, it is amazing to experience the changes in my body. I no longer have my daily fatigue. During the day I am filled with energy! I have much better sleeping quality and wake up in the morning full of freshness and energy! It has been months that I have not got sick or caught a cold, which usually was a problem for me in the past. There are a lot more incredible changes, which I can make a long list of. I feel confident again. I really appreciate the breadth and depth of knowledge covered in this course as well as the guidance and compassion I received from this course. I am very grateful to Dr. Mark for my health and wellness.