I don’t feel motivated?

Wow, that's a shocker! Don't worry, chap. Nobody enjoys doing homework - many hours of procrastination await you in future academia. The best advice I can give you is that it's better to read and completely understand your homework before you do it than doing it when you only half understand it. It sounds like adding another whole stage to your work, but trust me it will save you a lot of time in the end and you'll take more away from it.

Hello, Dung!Yeah, it's completely normal to not do something you don't want to. Don't worry. My advice is to take baby steps and do the homework bit by bit. Or finish it all at once, besides you have the rest of the time to do whatever you want. Have a good day!

Math can be a hard subject. I struggle a lot when doing my math's homework. But what keeps me motivated is the thought that, "Other people can do this, and why can't I?" this pushes me forward into doing the stuff that I don't really like. Sometimes in life, you have to go through all this bitterness to get to the sweetness of it all. So never give up Dung, there's always something.

Set points through your work, at each point (not every 2 mins, maybe 15+) have something good to do. "I feel a bit hungry....", hold until the next break, have a snack. "I want to see what's going on on Facebook", hold until the next break, do that. Set your breaks to points in your work, rather than just time and you'll do even better as you can't procrastinate to the next goal. Over time your brain will get used to this work/reward scheme and you'll find it easier and more automatic to do.