Rehabilitation for Arthritis of The Knee: mainTaining Improvement for Veterans

Inclusion Criteria: * Clinical diagnosis or chronic knee osteoarthritis. * Age between 40-90 years * Initiating physical therapy for KOA (has initial appointment within the next month or had first PT visit within the last 7 days) * To be randomized: PT feels that they are able to safely and reliably participate in ongoing exercise. * To be randomized: must have completed at least 4 virtual or in-person appointments with PT * To be randomized: must sync their Fitbit at least monthly. Exclusion Criteria: * Lack of a smart phone allowing interaction with the WTH platform * Inability to walk 2 blocks without assistance * Poorly controlled crystalline arthritis or other diagnosis of inflammatory arthritis. * Treating provider or LSI believes life-expectancy is \<1 year * Based on LSI or treating provider discretion: exclusions may occur for severe heart failure, unstable angina, end stage renal disease, severe chronic obstructive or other pulmonary disease, or other chronic illness felt to limit participants ability to participate in exercise or resulting in potential safety risk * Severe pain in a non-knee area limiting daily function * Non-English speakers or poor reading ability limiting ability to interact with text messages. * Pregnancy * Receiving physical therapy outside of the VA.