Everyone has their own dreams; what is big to you may be small to another and vice versa. No matter what anyone thinks about your dreams, they are yours and you should go after them. There are gonna be many obstacles to tackle while pushing for your dream one must know that. What everyone must know though is slightly different, everyone must know that failing is not always a negative thing. You can fail at something you thought was important and be pushed onto the right path of where you're supposed to be going for your dream(s).
You have big dreams, but something has happened to make you question if you can actually achieve your dream. YOU CAN! What you can accomplish is up to you and only you. Keep your mind open and your dreams growing and nothing can stop you. Your dreams are never too big to achieve and your confidence needs to shine. You cannot move forward with the journey to achieve your dreams if you do not take the next step up the staircase my friend. You may walk alone on your journey, and that is okay because it will be that more satisfying when you make improvements and achieve your dream.
No matter where you are in life, who you are around, and where you plan on going there is always going to be at least one person trying to bring you down; do NOT let that happen, show them what you can do and leave them behind in your past. Look and search for the light that is shining through the darkness of those around you. You will find that there are supporters rooting you on like a silent cheerleader in the crowd. Do not let your ambition die because of a few negative people, let it GROW.
Believe in yourself and all that you can be. Ask yourself, how am I going to prove people wrong if I don't have the confidence to believe in myself? You have already found something you think is worth fighting for, so go after it and fight for it. If someone who doesn't even know you believes in your dreams, how can you not believe in them and yourself?
Go out and make your difference to the world, even if it only betters yourself. You are getting ready for something bigger, and you will accomplish anything that you put your mind to.