The secret is to make a plan and stick to it no matter how difficult. Dreams cause people to put themselves through college, with part time jobs, start at the bottom of a company and work their way up to the top. Some with dreams start their own business. Many had a dream, but either did not develop a goal, or gave up on it when the going got tough.
You must believe in yourself to reach your dream. You have to believe in the meaning of your dream so much that it ignites your passion. Those without passion usually fail to reach their dream. You must believe in your ability to reach your dream. You have to want it so bad that you think about it when you eat, drink, and sleep. You must go after something that is reachable. That depends on your talent and ability to pay for the education needed.
You have to pick a field where you have God-given ability. It must be something that comes naturally and you do well in. It is helpful if you have friends that are supportive of your dream. You need encouragement from those around. If your friends are against your dream, you need to find other friends who are.