I started using the self-study course close to 10 years ago (mostly for depression and some minor but chronic issues I had been experiencing for a long time) About 5 years after that I met Chunyi and started going to retreats and classes. I found the self-study course to be amazingly empowering and helpful. Not only physically but mentally, emotionally and spiritually. The power of the self-study course is that it is carefully designed by Master Lin, for the westerner to use it safely, efficiently and profoundly. My practice deepened once I began to actually learn from Mr. Lin in person and I have since become much more confident in myself as a healer and when it comes to healing myself when needed. He does emphasize in Level 1, I believe, not to put energy directly into the heart.
I recommend reading Chunyi's book, Born A Healer, so you can learn about his life journey to Qigong and how he developed his philosophy and Qigong program that has been beneficial to so many people around the world.
Small Universe is a profound practice and in my experience the way Chunyi teaches it makes it easy to start anytime. The only side effects for me have been feeling really, really relaxed and good. I've done it so many times over the years and began with the self-study course. The combination of calling on unconditional love or your God to support you, deep breathing and visualization has kept me out of the doctor's office and functioning at peak performance in those areas of my life especially that are most important to me.
At the end of the day, trust your own judgement. Or go to a Spring Forest Qigong Retreat. Those are very helpful and Master Lin is there as well as other teachers who could answer your questions. Above all trust your heart. The deeper heart beyond the physical one and the emotional one is not at all defective. It is very wise. Best wishes.