Lethargy is a state of tiredness, weariness, fatigue, or lack of energy. It can be accompanied by depression, decreased motivation, or apathy. Lethargy can be a normal response to boredom, inadequate sleep, overexertion, overworking, stress, lack of exercise, or a symptom of a disorder. When part of a normal response, lethargy often resolves with rest, adequate sleep, decreased stress, and good nutrition.[21][22]

In conventional usage, boredom is an emotional and occasionally psychological state experienced when an individual is left without anything in particular to do, is not interested in their surroundings, or feels that a day or period is dull or tedious. It is also understood by scholars as a modern phenomenon which has a cultural dimension. "There is no universally accepted definition of boredom. But whatever it is, researchers argue, it is not simply another name for depression or apathy. It seems to be a specific mental state that people find unpleasant—a lack of stimulation that leaves them craving relief, with a host of behavioural, medical and social consequences."[1] According to BBC News, boredom "...can be a dangerous and disruptive state of mind that damages your health"; yet research "...suggest[s] that without boredom we couldn't achieve our creative feats."[2]
“I asked myself whether a life devoid of any affection, of any goal, a life one fills with a thousand trifles intended to relieve its monotony, populated with human beings one seeks out in order not to be alone and whom one flees to avoid being bored by them, whether such a life isn't ridiculous, whether anything whatsoever wouldn't be preferable.”
If he can maintain his concentration, Goetz intends to continue his own research into understanding the nature of boredom. He wants to measure physiological signs of arousal, which could one day add a new component to wearable health trackers. He’s also interested in investigating whether specific boredom types correspond to different age levels and cultures. “There are many important questions to be answered related to the boredom types,” he says.
“Boredom – the psychological state that we experience whenever we are uninterested in what we are currently doing – is one of the defining traits of humanity. Time is the psychological nemesis of humankind. Tedium, a fundamental angst of humankind, arises from human beings’ ability to perceive time and our attempts to derive meaning from our personal existence.”

^ Vodanovich, Stephen J. (November 2003) "Psychometric Measures of Boredom: A Review of the Literature" The Journal of Psychology. 137:6 p. 569 "Indeed, a shortcoming of the boredom literature is the absence of a coherent, universally accepted definition. The lack of an agreed-upon definition of boredom has limited the measurement of the construct and partly accounts for the existence of diverse approaches to assessing various subsets of boredom."
“Boredom is a flight from what is important. Like workaholism and perfectionism, it is a way of distracting yourself from inner experiences. It occurs when you look outward and do not find anything to engage your attention. Instead of feeling your emotions - becoming aware of the functioning of your energy system - you become bored. Boredom ... is a flight from your higher potential. It is fear of the transformation that wants to occur, and will occur in you, when you explore your emotions. It is your resistance to spiritual growth.”
Martin Heidegger wrote about boredom in two texts available in English, in the 1929/30 semester lecture course The Fundamental Concepts of Metaphysics, and again in the essay What is Metaphysics? published in the same year. In the lecture, Heidegger included about 100 pages on boredom, probably the most extensive philosophical treatment ever of the subject. He focused on waiting at railway stations in particular as a major context of boredom.[25] Søren Kierkegaard remarks in Either/Or that "patience cannot be depicted" visually, since there is a sense that any immediate moment of life may be fundamentally tedious.
Grunge lit is an Australian literary genre of fictional or semi-autobiographical writing in the early 1990s about young adults living in an "inner cit[y]" "...world of disintegrating futures where the only relief from...boredom was through a nihilistic pursuit of sex, violence, drugs and alcohol".[47] Often the central characters are disfranchised, lacking drive and determination beyond the desire to satisfy their basic needs. It was typically written by "new, young authors"[47] who examined "gritty, dirty, real existences"[47] of everyday characters. It has been described as both a sub-set of dirty realism and an offshoot of Generation X literature.[48] Stuart Glover states that the term "grunge lit" takes the term "grunge" from the "late 80s and early 90s—...Seattle [grunge] bands".[49] Glover states that the term "grunge lit" was mainly a marketing term used by publishing companies; he states that most of the authors who have been categorized as "grunge lit" writers reject the label.[49]
Flow is a state of total immersion in a task that is challenging yet closely matched to one’s abilities, akin to “being in the zone.” Flow occurs when a person’s skills match the level of challenge presented by the environment and when a task includes clear goals and immediate feedback. Tasks that are too easy are boring. In contrast, tasks that people perceive to be too difficult lead to anxiety.