Behavioral activation is considered a behavioral treatment that was originally designed to treat people with depression. It is focused on increasing your level of physical activity, with a particular focus on activities that you find rewarding and positive. Behavioral activation has been found to be very effective in reducing symptoms of depression.
Recently, it has been examined as a treatment for people with PTSD. This makes sense, as there is some overlap in symptoms between PTSD and depression, and many people with PTSD also suffer from depression. Several studies have found that behavioral activation on its own or combined with traditional treatments for PTSD can successfully reduce PTSD symptoms. You can learn more about behavioral activation and its relevance for people with PTSD in this article from About.com.