When you are interested in something, you don’t need motivation – the desire to do it is enough!
Sometimes though, when you’re trying endless stuff that doesn;t seem to be going anywhere, you just have to take a step back, deep breaths, and just keep going.
Thats the problem with finding out new knowledge, there’s lots of possibility for dead ends (and you find most of them on the way!)
I always set little targets and try and achieve them, for me that works really well. I have a friend that sets her alarm for 45 minutes, and if she studies and concentrates properly for 45 minutes, she gives herself a 10 minute break. If she’s learnt lots in the 45 minutes she rewards herself with snacks and treats! And then she goes back and studies for another 45 mins etc.