“A goal is not always meant to be reached, it often serves simply as something to aim at.”

When you set a goal, you get a thing to aim at which increases your confidence, focus and improves you. But, when you can't reach that goal, never ever become demotivated. A goal is just a guide for you which keeps reminding you to achieve something and if you can't achieve that goal, you have certainly achieved some fraction of it. I'll give you a tip, keep your goals according to this :- 

Specific	Measurable	Achievable	Realistic	Time bound
Goals should be simplistically written and clearly define what you are going to do. Include if necessary the What, Why and How.	Goals should be measurable so that you have tangible evidence that you have accomplished the goal.	Goals should be achievable; they should stretch you slightly so you feel challenged, but defined well enough so that you can achieve them. You must possess the appropriate knowledge, skills, and abilities needed to achieve the goal.	Goals should measure outcomes, not activities.	Goals should be linked to a timeframe.