Boredom was an emotion.
The Doctor frequently claimed that he had left Gallifrey because he was bored. (TV: The War Games, Voyage of the Damned, Heaven Sent) However, Davros believed that this was a lie. (TV: The Witch's Familiar) The Twelfth Doctor confessed it was a lie while inside his confession dial. (TV: Heaven Sent) The First and Fourth Doctors admitted that there several other "pressing reasons" at the time. (TV: Twice Upon a Time, Logopolis)
Things the Doctor found boring included studying Druidic lore, (TV: The Stones of Blood) the Vulgar End of Time, (AUDIO: The One Doctor) the two weeks he ran Taunton in the 18th century, (PROSE: The Highest Science) sitting watching the cubes all day (TV: The Power of Three) and Earth in 2105. (TV: The End of the World)