Participants in the treatment group will receive the 12-week STEP by a trained interventionist. In the first four weeks, the interventionist will focus on building participants' selfefficacy and health literacy and help participants learn the STEP exercise and principles. In the following four weeks, the interventionist will help the older adults to be more independent in prescribing exercise activities for themselves. In the last four weeks, participants will be fulling knowledgeable and independent on functional exercising; the interventionist will allocate community resources for long-term maintenance. After program completion, trained raters will administer at post-tests. There will also be a 3-month and 6-month follow-up evaluation after program completion.

Participants in the control group will receive weekly health newsletters and will not get any suggestions or encouragement to do exercise from the research team. A staff member will call the control group participants weekly to document any new exercise programs from usual community services. At this stage, participants will not be excluded from the study if they join an exercise program, but we will document what kind of exercise they are conducting. Trained raters will administer at post-tests and two follow-ups.

Treatment group will receive the 12-week STEP by a trained interventionist. During the intervention period, an occupational therapist will help the participant to learn the STEP exercise and principles and help the older adults to be more independent on functional exercising.

Using a handheld dynamometer (MicroFET2, MMT) to measure the maximal isometric knee strength of the dominant leg with a standardized protocol.

Skeletal muscle mass will be measured by a portable Bio-impedance analysis (BIA) instrument at 50hz (Yida muscle mass and strength analyzer; YD01A), which had preliminary valid data for Taiwanese older adults and can be easily carried to community settings.

The Short Physical Performance Battery (SPPB) is an assessment of lower extremity function with three subtests: (1) standing balance, (2) four-meter gait speed, and (3) five repetitions of sit-to-stand motion.

Reach includes recruitment and retention rates. Adoption will be surveyed among participants and service networks at post-test. Adherence will be measured by the average number of activities recorded in the STEP activity planner. Fidelity is defined as treatment delivery, treatment receipt, and treatment enactment.

Self-Reported Habit Index (SRHI), a self-rated assessment, which incorporates constructs such as habit strength, frequency, relevance to self-identity, and automaticity. Higher scores indicate that behavior is more strongly habitual.