On one hand, this quote reminds me a lot of dealing with a particularly frustrating customer service department. The front-line folks generally have very little power to solve problems, they just listen to your complaint, apologize, and then do nothing. Don't ever take that as your answer! Speak to as many people as it takes until you have reached someone who can actually help.
On the other hand, and in a more big-picture sense, this quote can really make you think about who actually has power over your dreams and goals.
Often, there are people around us that make our dreams seem like impossibilities.
Have you ever allowed another person's negativity to affect your motivation? Did they tell you that your dream was too big, that your goal was too hard to reach? Did they go out of their way to remind you of all of the insurmountable (to them) obstacles you would face? Here's the thing - no matter who that person was - parent, boss, spouse, friend - they don't have the power to make that dream come true for you. So, don't let them tell you no.
The one person in the world that has ultimate control over your dreams is... you guessed it, YOU. Remind yourself of that daily, and keep a silent, reassuring YES always in your heart.