I can totally relate to no motivation and feeling like everything is boring. Sometimes I get so I can't even focus to watch TV, and forget reading a book, which I uusally love. For me it's a sign of low grade depression. Not full blown major depression, more more like ongoing, nagging dysthymia. It's not even that awful, it's just like nothing really matters.

For depression to be diagnosed you don't actually have to have a low mood. The criteria are at least one of low mood and/or loss of interest/loss of pleasure, plus at least 4 other symptoms (3 other symptoms if you have low mood and loss of interest).The other symptoms are change in appetite, insomnia or hypersomnia, fatigue, psychomotor restlessness or slowing, poor concentration, and thoughts of death. So you could be depressed, even if your mood is normal, if you have enough of these symptoms.