What can you do about boredom? Obviously, there are times when you are stuck. If you are listening to a lecture that you cannot leave, then you just need to find a way to get through it. When you have some control, though, use your understanding of boredom to help you out. If you can, try to do a meditation exercise to lower your arousal level. Also, keep some music handy. Music you enjoy can crowd out distractions in the environment. It can also influence your mood in positive ways to counteract the pain of being bored.  
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 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]
People who lack self-awareness are more prone to boredom. A bored individual is unable to articulate what it is that he or she desires or wants to do. They have trouble describing their feelings. An inability to know what will make one happy can lead to a more profound existential boredom. Not knowing what we are searching for means that we lack the capacity to choose appropriate goals for engagement with the world (Eastwood, 2012).

Boredom also plays a role in existentialist thought. Søren Kierkegaard and Friedrich Nietzsche were two of the first philosophers considered fundamental to the existentialist movement. Like Pascal, they were interested in people's quiet struggle with the apparent meaninglessness of life and the use of diversion to escape from boredom. Kierkegaard's Either/Or describes the rotation method, a method used by higher level aesthetes in order to avoid boredom. The method is an essential hedonistic aspect of the aesthetic way of life. For the aesthete, one constantly changes what one is doing in order to maximize the enjoyment and pleasure derived from each activity.
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.
The French loanword ennui comes from the very same Late Latin word that gave us annoy — inodiare ("to make loathsome"). We borrowed ennui several centuries after absorbing annoy into the language. Ennui deals more with boredom than irritation - and a somewhat specific sort of boredom at that. It generally refers to the feeling of jadedness that can result from living a life of too much ease. The poet Charles Lloyd described it well in his 1823 Stanzas to Ennui when he referred to that world-weary sensation as a "soul-destroying fiend" which visits with its "pale unrest / The chambers of the human breast / Where too much happiness hath fixed its home."