This article was medically reviewed by Ni-Cheng Liang, MD and by wikiHow staff writer, Dan Hickey. Dr. Ni-Cheng Liang is a board certified Pulmonologist and the Director of Pulmonary Integrative Medicine at Coastal Pulmonary Associates affiliated with the Scripps Health Network in San Diego, California. She also serves as a Voluntary Assistant Professor of Medicine at the University of California San Diego School of Medicine while volunteering for the UCSD Medical Student-Run Free Clinic for uninsured patients. With over 15 years of experience, Dr. Liang specializes in pulmonary and respiratory medical concerns, mindfulness teaching, physician wellness, and integrative medicine. Dr. Liang received her Doctor of Medicine (MD) from the University of Maryland School of Medicine. Dr. Liang was voted as a San Diego Top Doctor in 2017 and 2019. She was also awarded the 2019 American Lung Association San Diego Lung Health Provider of the Year. This article has been viewed 5,731,085 times.