But you must do it to create an atmosphere that will permit you to concentrate. If you are not careful, you'll lose your forward motion. This can happen if you read so fast you miss the meaning of the words. You will reach a point of diminishing returns in any prolonged study period. Don't force yourself too far beyond your natural study limits.
Most students can concentrate better and study harder if they have set up an immediate reward.
From The College Experience by E.N Chapman, page 20.