First thing, remember that Allah is always with us. Everything that is happened is good for us from Allah. Sometimes dreams do not come true. we do not lose hope.
Example
I have one example of student. Suppose one student wish to become a doctor. He struggles in matric very much and also he gets output of this, at FSC level, he became ill and he couldn't struggle as he does in matric and he does not fulfill the criteria of becoming doctor. So, he goes onto another field like bachelors in Chemistry, so he continues his degree and also he thought between his degree that i wished to become doctor and also , he wished that he helps the poor patients and is very kind to the patients. But whatever is happening there is in Allah's will. Allah knows what is best for us.
In his bachelor's degree, if he wants to become a teacher after his degree, he can kind to the students , he can have friendly behavior with students, he also shares the good and bad things with students, give motivational stories. He fulfill his duty like that he thought after becoming doctor. Trust me students like him very much and follow him.
###Remember every person has one dream of his life which he holds within itself through out life.
So whatever yours goals are, if you don't achieve your goals in your life Choose another way and try your best. Because Allah knows what is best for us.