Despite considerable attention to fatigue in acute and chronic illnesses, little is known about fatigue in a healthy population. A detailed exploration of fatigue, therefore, was conducted to answer the broad question of what fatigue is to a basically healthy population and to lay the groundwork for establishing an empirically based definition of fatigue. Qualitative and quantitative methods were used. Results of the qualitative phase of the study, in which 40 persons were interviewed, are presented here. Categories and themes of the experience of fatigue were identified. Based on the qualitative findings, we propose that fatigue in generally healthy adults is an acute, subjective, sometimes overwhelming, but temporary state (with physical, emotional, and behavioral manifestations) caused by stress and overwork in one's life roles, which disrupts activity and alerts the person to take restorative measures.