Boredom also has its benefits. It is important to see boredom as a “call to action” (Svendsen, 1999). Nietzsche suggested that men of rare sensibility value boredom as an impetus to achievement. Boredom can be a catalyst for action. It can provide an opportunity for thought and reflection. It can also be a sign that a task is a waste of time—and thus not worth continuing.
In Experience Without Qualities: Boredom and Modernity, Elizabeth Goodstein traces the modern discourse on boredom through literary, philosophical, and sociological texts to find that as "a discursively articulated phenomenon...boredom is at once objective and subjective, emotion and intellectualization—not just a response to the modern world but also a historically constituted strategy for coping with its discontents."[3] In both conceptions, boredom has to do fundamentally with an experience of time and problems of meaning.
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]
The bored antihero became prominent in early 20th century existentialist works such as Franz Kafka's The Metamorphosis (1915),[43] Jean-Paul Sartre's La Nausée (1938) (French for 'Nausea'),[44] and Albert Camus' L'Étranger (1942) (French for 'The Stranger').[45] The protagonist in these works is an indecisive central character who drifts through his life and is marked by ennui, angst, and alienation.[46]
These authors suggest that attention plays an important role in creating boredom. In particular, there are a few conditions that need to be met for people to feel bored. First, people need to have a reasonable level of psychological energy or arousal to feel bored. When people have low arousal and there is not much happening in the world, then they often feel relaxed. When they have high arousal, though, they have energy they would like to devote to something, but they cannot find anything engaging.
“Alcohol makes other people less tedious, and food less bland, and can help provide what the Greeks called entheos, or the slight buzz of inspiration when reading or writing. The only worthwhile miracle in the New Testament—the transmutation of water into wine during the wedding at Cana—is a tribute to the persistence of Hellenism in an otherwise austere Judaea. The same applies to the seder at Passover, which is obviously modeled on the Platonic symposium: questions are asked (especially of the young) while wine is circulated. No better form of sodality has ever been devised: at Oxford one was positively expected to take wine during tutorials. The tongue must be untied. It's not a coincidence that Omar Khayyam, rebuking and ridiculing the stone-faced Iranian mullahs of his time, pointed to the value of the grape as a mockery of their joyless and sterile regime. Visiting today's Iran, I was delighted to find that citizens made a point of defying the clerical ban on booze, keeping it in their homes for visitors even if they didn't particularly take to it themselves, and bootlegging it with great brio and ingenuity. These small revolutions affirm the human.”
One more key element of boredom is control. Boredom often occurs when you have little control over your situation. Waiting rooms, lectures, and airline gates are all places where you have little control over your situation. Normally, we react to unpleasant situations by changing the situation. If you don’t like a book you are reading, for example, you close it and do something else. Boredom happens when you are unable to change the situation.  
The expression to be a bore had been used in print in the sense of "to be tiresome or dull" since 1768 at the latest.[4] The expression "boredom" means "state of being bored," 1852, from bore (v.1) + -dom. It also has been employed in a sense "bores as a class" (1883) and "practice of being a bore" (1864, a sense properly belonging to boreism, 1833).[5] The word "bore" as a noun meaning a "thing which causes ennui or annoyance" is attested to since 1778; "of persons by 1812". The noun "bore" comes from the verb "bore", which had the meaning "[to] be tiresome or dull" first attested [in] 1768, a vogue word c. 1780–81 according to Grose (1785); possibly a figurative extension of "to move forward slowly and persistently, as a [hole-] boring tool does."[6]
There are three types of boredom, all of which involve problems of engagement of attention. These include times when we are prevented from engaging in wanted activity, when we are forced to engage in unwanted activity, or when we are simply unable for some other reason to maintain engagement in an activity.[13] Boredom proneness is a tendency to experience boredom of all types. This is typically assessed by the Boredom Proneness Scale.[14] Recent research has found that boredom proneness is clearly and consistently associated with failures of attention.[15] Boredom and its proneness are both theoretically and empirically linked to depression and similar symptoms.[16][17][18] Nonetheless, boredom proneness has been found to be as strongly correlated with attentional lapses as with depression.[16] Although boredom is often viewed as a trivial and mild irritant, proneness to boredom has been linked to a very diverse range of possible psychological, physical, educational, and social problems.[19]

This example leads to another key aspect of boredom. As Eastwood, Frischen, Fenske, and Smilek point out, bored people become aware of their difficulty concentrating. As a result, bored people often try to amuse themselves by daydreaming and letting their mind wander. Interestingly, while mind wandering helps people to keep their minds occupied, studies suggest that the more your mind wanders, the more bored you feel. The idea is that you recognize that this daydreaming is meant to occupy your mind, and so you realize that the situation is boring.

There was also a piano, well littered with music, a sewing bag thrown down upon a cretonned window seat, and the generous fireplace was flanked by two huge baskets, one heaped with magazines, the other a perfectly round mound of yellow fur, which suddenly took form and life as a yellow tabby cat fastened hopeful topaz eyes upon them, blinked away a brief disappointment, and then yawned with ennui.