Smucker, Mervin (2013). Overcoming Depressive Moods, Lethargy and Inactivity by Significantly Increasing One’s Level of Activity.

Pessimistic thoughts and negative predictions about upcoming activities or events (e.g., „I would not enjoy myself“, „No one would talk to me“, „I would look like a social misfit“, „I’m too tired to do anything“) can result in a loss of interest in activities, low energy, chronic fatigue, and social isolation. The deeper one sinks into a state of lethargy and inactivity, the more depressed one feels, the less one feels like doing anything from which one could derive pleasure or a sense of accomplishment. This vicious cycle is propelled by negative thoughts that arise whenever one thinks about engaging in an activity.

One method for reversing this cycle of inactivity is to plan activities for each day and then to push onself to engage in these activities, regardless of how difficult this may be. The goal is not necessarily to accomplish everything on one’s activity schedule, but to become more externally-focused (and less internally-focused!) by increasing one’s level of physical activity. Clinical research on depression and activity clearly indicates that increasing one’s level of physical activity by itself is a significant mood elevator, a kind of behavioural anti-depressant. In short, the more active one is, the better one feels, and the better one feels, the more active one is likely to be.

Mervin Smucker on strategies to deal with depressions (German)