Focus on your goal. Don't look in any direction but ahead. Repin. Once you've decided on your career do this, people come and go but your education never leaves you. Oh and some will deliberately scupper your education, so concentrate on yourself, don't worry about them.
What screws us up most in life is the picture in our head of how it's supposed to be. For more quotes and inspirations: http://www.lifehack.org/articles/communication/what-screws-most-life-the-picture.html?ref=ppt10