You've probably seen motivational posters hanging on office walls in reality or on television. Some of them seem silly, but they can really help motivate you when you're not in the mood to get your work done. You should hang one up in your room in order to see for yourself. If you don't want to buy an actual motivational poster, here are a few uplifting quotes from them that you can print out to hang on your wall:
It doesn't matter what you're trying to accomplish in life, because you're always going to be met with obstacles. However, you shouldn't let them deter you from your goals. Don't even pay attention to those obstacles if they force you to take your eyes off of the prize. Focus on what you're doing and let everything else become background noise.