疲勞是人們向醫生、朋友和親屬最常抱怨的問題之一。現代疲勞癥的原因各種各樣，只是很少與過量的體力消耗掛起鉤來。相對人數不多的整天從事重體力勞動的那些人幾乎從來不抱怨勞累，也許因為他們預料到會感到疲勞。今天，醫生報告說，疲倦更可能是由于活動不足所致，而不是活動過量所引起的。其實，增加體力活動常常是為治愈人們體力衰退所開的一個藥方。

　　Fatigue is one of the most common complains brought to doctors, friends and relatives. The causes of modern-day fatigue are diverse and only rarely related to excess physical exertion. The relatively few who do heavy labor all day long almost never complain about being tired, perhaps because they expect to be. Today, physicians report, tiredness is more likely a consequence of under-exertion than of wearing yourself down with over-activity. In fact, increased physical activity is often prescribed as a cure for sinking energy.