Introduction: Veterans with mental illness tend to have shorter life spans and suboptimal physical health because of a variety of factors. These factors include poor nutrition, being overweight, and smoking cigarettes. Nonphysical contributors that may affect quality of life are the stigma associated with mental illness, social difficulties, and spiritual crises. Current mental health treatment focuses primarily on the delivery of medication and evidence-based psychotherapies, which may not affect all the above areas of a Veteran’s life as they focus primarily on improving psychological symptoms. Clinicians may find greater success using integrative, comprehensive, multifaceted programs to treat these problems spanning the biological, psychological, social, and spiritual domains. These pilot studies test an adjunctive, holistic, behavioral approach to treat mental illness. This pilot work explores the hypotheses that engagement in a greater number of therapeutic lifestyle changes (TLCs) leads to improvement in quality of life, reduction of psychiatric symptoms, and weight loss. Materials and Methods: Institutional Review Boards for human subjects at the Veterans Affairs (VA) Greater Los Angeles and Long Beach Healthcare Systems approved pilot study activities at their sites. Pilot Study 1 was a prospective survey study of Veterans with mental illness, who gained weight on an atypical antipsychotic medication regimen, participating in a weight management study. At each session of the 1-year study, researchers asked a convenience sample of 55 Veterans in the treatment arm whether they engaged in each of the eight TLCs: exercise, nutrition/diet, stress management and relaxation, time in nature, relationships, service to others, religious or spiritual involvement, and recreation. Pilot Study 2 applied the TLC behavioral intervention and examined 19 Veterans with mental illness, who attended four classes about TLCs, received individual counseling over 9 weeks, and maintained journals to track TLC practice. Besides weekly journals, researchers also collected prospective data on quality of life, psychiatric symptoms, vitals, and anthropometric measurements. In both studies, investigators tested for main effects of the total number of TLCs practiced and study week using mixed-effects linear models with independent intercepts by participant. Results: In Study 1, engagement in more TLC behaviors was significantly associated with higher ratings of quality of life, as well as greater weight loss for each additional type of TLC practiced. In Study 2, TLC practice increased significantly over 9 weeks, and was significantly associated with improvements in quality of life and diastolic blood pressure. Conclusion: Counseling Veterans to practice TLCs provides a holistic adjunct to current treatments for mental illness. TLCs may confer multiple benefits upon Veterans with mental illness, enhancing quality of life and well-being along with weight management efforts. As these were pilot studies, the samples sizes were relatively small and a control group was lacking. Our findings may have broader implications supporting a holistic approach in both primary and mental health care settings. Future research will expand this work to address its weaknesses and examine the cost differential between this holistic approach and traditional mental health treatment.