Many of my students and young friends are facing lots of tests and homework, and feel pressured. I would like to make a suggestion which may help to make it easier to study. Whatever you are studying, try to find a small part that you do better than other parts, and concentrate on doing that part well. When a problem is solved, you will feel good. Stop and enjoy that moment of success. Repeat that process with something that is slightly more challenging. Gradually you will get better and better at it, you will be able to concentrate better, and you will enjoy the process better.
In time, you will study for the joy of discovery, of overcoming a challenge, not just because you have to do it. You will achieve a state of "flow" while studying - a most enjoyable experience. I learned this from personal experience, and also from a lot of serious research done by psychologists such as Mihaly Csikszentmihalyi.