If you struggled this semester for whatever reason and feel defeated, pick yourself up and finish strong! Take advantage of the next two weeks to study for semester tests, complete missing assignments, and/or ask about extra credit projects.  Teachers may be willing to work with you if your appeal for grace is humble and sincere.  

Get yourself pumped up, surround yourself with supportive friends, focus, and make a commitment to finish strong. You can raise your grades and start off your summer with a great sense of freedom (and the wonderful sound of your parents NOT harping on you). Bring that "D" up to a "C" or that "C" up to a "B". If you're really in hot water and failing, don't give up! Never give up! Talk to your teachers and do whatever they suggest with 100% effort. 

Your teachers want you to succeed!  Talk to them. Make a plan. Work hard for two weeks. Bring up your grades. Feel good. Enjoy your summer.