The purpose of this research is to understand how chronic stress affects the way our brain and immune systems function, and in turn how this affects the way people feel, think, and behave. By learning more about how these processes work, the hope is to be able to develop better treatments to help with problems like depression and substance use. This study is intended for individuals that are HIV positive, currently taking prescription antiretroviral medications, and use stimulants. Through this intervention, the aim is to determine if this positive affect intervention can lead to reductions in stimulant use and depressed mood.