This aim of this research project is to determine if low to moderate level exercise can have an impact on stress, fatigue, and quality of life for individuals diagnosed with a primary immunodeficiency disease. Many individuals diagnosed with primary immunodeficiency disease report chronic fatigue and/or pain, which can potentially limit their participation in exercise and physical activities. Research shows that regular exercise can improve both physical and mental health for individuals diagnosed with a chronic medical condition. Exercise is a healthy and low-cost alternative to some medications, and may be an effective addition to the treatment plan for many patients with primary immunodeficiency disease. Research also suggests that low level exercise may be beneficial to immune function, while intense, or prolonged exercise can be harmful. This 8-week study will compare participants engaging in a semi-customized, home exercise program (exercise intervention group) to participants performing normal activities (non-exercise control group). This study will track stress, fatigue, and quality of life, using standardized questionnaires, journals, and interviews. Weekly contact will be made with all participants throughout the 8 weeks of the study. Individuals in the exercise group will be asked to complete up to 150 minutes of exercise, per week, at the 11-14 rating of perceived exertion. Participants who are randomized to the control group will continue their normal activities; they will also be given the opportunity to participate in the exercise program at the end of the 8 week study. To help assess the safety of a low to moderate level exercise program for individuals with primary immunodeficiency disease, this research will track the number of infections, non-planned medical visits, or increased medication usage during the study (compared to 8 weeks prior to the intervention). This research will help provide valuable information about the safety and effectiveness of an exercise program for individuals with a primary immunodeficiency disease.