Inclusion Criteria:  Participants will be recruited if they  age ≥ 55 years, have consulted healthcare professionals (e.g., general practitioners, physical therapists, Chinese medicine practitioners) with pain, stiffness, or both in one or both knees; or have knee pain, stiffness, or both in one or both knees on most days for at least one month during the past 12 months, report having moderate or severe knee pain (an average pain score of 4 or more on an 11-point numerical rating scale) in one or both knees, are able to perform the exercise required in the study, are able to speak and read Chinese, are able to provide written informed consent.  Exclusion Criteria:  Individuals will be excluded if they have  inflammatory arthritis, acute trauma, malignancy, history of knee replacement, being on the waiting list for knee surgery, physical therapy for knee problems during the past three months, intra-articular injection to the knee within six months.