Extract from an interview with a Tai Chi Chuan master
Interviewer: Often there are people who practice Tai Chi Chuan for 10, 15 years and achieve no power. What advice would you give to these people?
Master: Obviously this individual did not have a good teacher. Stop and find someone else. As I said before, you should find a knowledgeable teacher, not just a famous one.
Generally a knowledgeable teacher will be someone whom very few people know of and who is difficult to find.