Inclusion Criteria:  are 18 years old and above; have not maintained 30 minutes of MVPA accumulated per day for 2 days of the week during the previous 6 months; have a score < 24 for the leisure score index of the Godin Leisure-Time Exercise Questionnaire; be relapse-free for the past 30 days; show low risk for contraindications of PA indicated by no more than a single 'yes' response on the Physical Activity Readiness Questionnaire; be able to walk with or without an assistive device; are willing to be randomized to an intervention or control group, complete the surveys and questionnaires, and wear an accelerometer during the intervention period; have Internet access.  Exclusion Criteria:  -