The motivation is there, that's just good grades are not easy to get. In order to raise their performance to a higher level, should review your training. This analysis should answer the main question: what prevents me to learn for the best grades? If you find the cause (why do you learn bad), then the effect (fix the situation for the better) will not make you wait long.
1. Lack of desire to learn.
Few of today's students and pupils experiencing rare passionate desire to acquire new knowledge, to gnaw granite of science. This philosophy has a certain basis. Many students believe that the age of the teaching for a long time has passed since almost any information can be gleaned from the Internet. So do not waste your best years of his life for sitting behind the textbooks in the classroom or the lessons. However, this approach to learning is often "goes sideways" into adulthood and during professional dissertation writing.
2. The presence of "prosperous future."