I would say that boredom is the opposite side of the coin of creativity. When well balanced it looks like a balanced group of habits that goes from productivity at full strength (because all animals need jobs) to time taken off enjoying mindless entertainment or pointless hobbies to relax (because sometimes work is too much).

I bet when one notices a lack of motivation, it's a lack of motivation in a certain arena, not motivation in general, a lack of motivation to what one think they SHOULD be doing.