Fellow , how do you keep yourself motivated to learn something which you are not interested in?

I know this sounds a little bit illogical, but try to read around the subject more and find some aspect of it that you do find interesting, and then you are likely to find the whole subject more interesting and it then becomes so much easier to motivate yourself, e.g. when I had to learn the periodic table in school, we were just told to learn parts of it, and just memorising it is boring, but then I read up about Mendeleev, how he came up with the periodic table, his life and how he predicted elements existing before there was proof of them, and it instantly became more interesting to me, and so much easier to learn. I genuinely believe that no subject is boring if you know enough about it. If you can't find an angle that interests you about a specific subject, try talking to someone who does find it interesting and ask them what they find interesting about it.