To the student who lacks a fully formed sense of internal motivation, offering an external motivator in the form of a reward could be the secret to inspire learning. Humans of all ages, kindergarteners or college students, tend to repeat behavior that is rewarded, thus it becomes incumbent on the teacher to figure out what sort of reward would be appropriate and effective. Younger students might thrive on a piece of gum or small toy, while older students find motivation in exemption from a test or free movie certificate. The point is that these types of extrinsic motivators create an internal sense of motivation, even if only for a short time.
A teacher should not be surprised to find that the class, as a whole, might be more receptive to a decidedly visual approach to the learning process. Having grown up with computers, video games, and television in every room of the house, each successive generation of student seems to be more geared toward the idea of seeing is believing than the one before. This doesn't mean you should continually screen movies, but drawings, diagrams, pictures, charts, and even 3D objects can help attach an idea to a visual image.
A teacher's job is tough but, as a professional, it's up to you to be "on" and oozing energy for every class, even the one directly after lunch. Ben Stein's famous character from Ferris Bueller's Day Off is not too far off the mark from the droning, robotic approach found in some classrooms. Try bringing the energy and enthusiasm to every class and you might be surprised at the increased interest and learning that takes place.
Few people in this world don't appreciate a bit of praise from those in power, such as a teacher. This method costs so little, takes barely any time at all, and can yield enormous dividends. Try writing a personal comment on a paper or stopping by a student's desk to recognize him for a job well done. To those starving for attention and recognition, these simple gestures might be all that's needed to kick-start a lifetime of learning.