The authors of this paper point to an interesting study by Robin Damrad-Frye and James Laird in the August 1989 issue of the Journal of Personality and Social Psychology. In this study, participants had to listen to a tape of a person reading a Psychology Today article. In the next room, there was a television soundtrack from a soap opera playing. For some groups listening to the article, the TV was very loud and distracting, for others it was barely noticeable, and for some it was not playing at all. After listening to the article, people rated their boredom during the study. 
Second, boredom typically occurs when people have trouble focusing their attention and they believe the reason for this difficulty is in the environment. When sitting in the airport, for example, there is probably a lot going on. There are people having conversations that you could listen to. You probably have something to read. There may be televisions showing the news. But, the stress of waiting for a delayed flight often makes it hard to concentrate, and so your mind jumps from one thing to another. You assume that this is caused by the environment, and so you feel boredom.
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.  

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).
When the antiproton was discovered … it sent a wave of ennui through the physics community. Not that its discovery was unimportant, but on the basis of Dirac's theory, everybody expected it. — Roger G. Newton, The Truth of Science, 1997 Chauncey and I were keen enough about our aesthetic solution to the ennui of war to try to proselytize others. He organized discussion groups with the crew; I took volunteers to visit landmarks … — Louis Auchincloss, "Atlantic War," in Authors at Sea, ed. Robert Shenk,  1997 The attendant outside was standing on tennis balls, exercising the soles of her feet, her body swaying back and forth with the ennui of jelly. — Edna O'Brien, New Yorker, 17 June 1991 Thus the days of life are consumed, one by one, without an object beyond the present moment; ever flying from the ennui of that, yet carrying it with us … — Thomas Jefferson, in a letter dated 7 Feb. 1787 Thomas Jefferson: Writings,  1984 the kind of ennui that comes from having too much time on one's hands and too little will to find something productive to do