Your attitude towards yourself, people and situations sets the stage on whether you bounce back easily or find yourself in the dumps.
Surround yourself with something or someone that makes you happy no matter what! If your new puppy always makes you smile, make sure to set aside time to play with her. If playing woodwind instruments at musicians friend makes you forget that awful Algebra quiz which you think you failed, make it a point to practice playing them every evening.
Be thankful for the good things. Before you sleep at night, instead of dwelling on that disagreement you had with your best friend, think of the good times you had with her and text her and tell her can you be friends again.