This won't work for everyone, and even works on myself only half the time, but changing the way you view motivation might help.
Motivation isn't waking up one day and being all like "You know what? I feel like working today. I have motivation today. Today, methods looks interesting enough to study for". It's just not. Sometimes it can be but most of the time it isn't.
Motivation is waking up and being "Fuck this shit, I can't write an essay today and I'm way too tired" and then knowing you need to study and sitting down and doing it anyway (albeit very slowly).
I find that if you look at motivation as a long term, slow burning thing as opposed to sudden bursts of studyphilia then you recognise that just because you feel 'unmotivated' doesn't mean you're not going to get work done.
But like I said before, changing this way of thinking doesn't always work for everyone. Perhaps you're already in the second frame of mind and the lack of a "burst" makes it really hard to study. I don't know. Just sharing something that works for me when I feel like not studying.