The concept being: Lethargy or apathy caused by a continuous cycle of dissatisfaction caused by disinterest from exposure.
The best way I can think to elaborate is to describe it as a state where you no longer care to strive because it is inevitable that the thing which you strive for will eventually no longer be interesting.
Similar to the Buddhist idea of sankhara-dukkha : "A basic unsatisfactoriness pervading all existence, all forms of life, because all forms of life are changing, impermanent and without any inner core or substance."