This is a Hybrid 1, effectiveness-implementation study of yoga-based exercise (YE) as an adjunctive tool for rehabilitation among persons with Severe Mental Illness (SMI), defined here as schizophrenia (SZ), schizoaffective disorder (SZA) and bipolar I disorder (BP1). SMIs are common, severe and devastating conditions that cause enormous disability world-wide. Many features of SMI can be treated effectively, yet the long-term outcome has not improved much over the past century. The lack of improvement may be due to ineffective treatment of functional deficits in SMI patients, particularly in terms of community functioning, defined here as social, leisure, employment, and life skills functioning in the community. Complementary and Integrative Medicine (CIM) therapies that improve community functions are thus of great interest for treating Veterans with SMI and thereby target an area of high priority for the VA. Prior studies have shown short-term benefits of YE for improving cognitive deficits and community functions among persons with SMI. While the published studies are encouraging, the longer-term benefits of YE are untested, particularly for community functioning. The profile of Veterans with SMI who will accept and adopt YE is also unknown. We have conducted pilot studies and a randomized controlled trial (RCT) for individuals with SMI in India using short-term, simplified YE combined with medications. Recently, we also concluded RELIEVE, a RCT of adjunctive YE for Veterans with post-traumatic stress disorder (PTSD) in the USA (VA RR&D Merit award, PI: L Davis, PsyD). We found encouraging improvements from all our studies, but our Indian and US YE protocols are impractical for Veterans with SMI. For example, some postures may be difficult for older Veterans with amotivation and/or physical disabilities. Therefore, in Aim 1, we will design and evaluate adaptations of the Indian and US YE protocols in a non-religious context (mindfulness, stretching, toning and breathing exercises). We will consult our Indian and US colleagues, our Veterans with SMI and their VA therapists to adapt the protocol for our SMI population. We will also adapt our control condition, the Wellness Lifestyle Program (WLP), from our recently completed RELIEVE study. In Aim 2, we will conduct a 2-armed RCT in which consenting Veterans with SMI will be randomly assigned to one of 2 arms: YE and treatment as usual (TAU, any prescribed treatment) or WLP+ TAU. Unlike prior short-term YE RCTs, the two arms will continue 12 months, including an initial 12-week training period consisting of two supervised sessions per week, followed by a 12-week training period consisting of one supervised session per week, and monthly refresher training sessions offered for the remaining 6 months. We will conform to all COVID-19 related requirements for YE and WLP. Our Hybrid 1 trial will compare the efficacy of YE versus WLP. Primary outcomes are self-report and performance-based measures of co...