I have pretty severe problems with motivation. When I'm in a class I don't enjoy, I do not feel like working at all. This reminds me of something an old biology teacher told me.
"As your teacher I feel obligated to mention you should be on task in all your classes. When I was a student in a course that I felt was not challenging me, I reminded myself that every person has a unique set of experiences. Even when the professors were lecturing about topics for which I was well versed I adopted the view that I will learn something from them because they have a different perspective and this person has knowledge that I would not acquire otherwise, therefore I engaged myself in the moment of learning. Adopting this attitude allowed me to relax and find something new to learn. I also perceive each of my students as unique and carrying knowledge that would allow me to better understand the world and the dynamic society we live in together."
I'm not saying my teachers don't have anything to teach me. I know they do. In fact, I enjoy learning in every single one of my classes. The problem is this: I become frustrated when I have to complete menial work on top of that knowledge. This work doesn't interest me. I could read Shakespeare and discuss the applications of recursive functions all day, but I could not care less about filling out worksheets displaying my knowledge of genetics.
I think part of my motivation stems from what I think will be applicable in my life. I have no plans for going into plant science, but I'll be able to read Shakespeare and program for the rest of my life. I don't see why it should matter whether or not I fill out a worksheet over things I already know. This humdrum work frustrates me to no end.
I need advice. How do I stay motivated enough to complete assignments for classes? What philosophies can you share? How do I make this work enjoyable?
When you find the answer to this question let me know. I have had the same issue my whole life. I don't know how old you are, so I'm sorry if guessing high school would be an underestimation. The reason I assumed that age range is because I had these exact problems with motivation for my whole high school career, but now I'm in college and they've almost entirely gone away (and were sent directly to other areas of my life, but that's a different story). I've found that college work is more meaningful - no "busy work", and for some classes no homework at all. Not only that but also once you are working towards a degree in something, you don't have to spend much time learning about things that don't interest you.
I realize this isn't very helpful information for you now, regardless of whether you're in high school or college. But when I had classes I couldn't stand, I don't remember ever having a strategy for dealing with them. I hated every minute of it and was selectively lazy about the work, but in the end the grade was mine for the taking. If you know you're capable of doing it, you might as well just power on through. A good grade for its own sake can be pretty satisfying.