We've heard this phrase in the affirmative many times. Many people believe that wanting is enough. This isn't true, and it never has been. Wanting is wanting; being able is something else entirely. I want to travel to Europe tomorrow. Can I? I really can't. I have obligations and a lack of money that prevent me from doing so. Therefore, wanting is not enough.
If it's possible to give it a different interpretation, it's this: I realize I want to go to Europe, but tomorrow is impossible. Therefore, I look for ways to make my trip to Europe possible at some point. I focus on it. I persist in it; I'm pure willpower in it. I don't sacrifice myself, nor do I give my best effort. This is because both sacrifice and effort are often unsustainable in the long run. This leads us to other phrases created by the ego: "Sacrifice yourself," "Give your best effort." It leads nowhere. And if you've set expectations and don't achieve them, you'll feel frustrated and therefore feel like a failure, and your ego will tell you: "You are a failure."
That's ego nonsense. Interpret it as steps; they're steps that lead me to success, and it's not up to me to know how many steps I need to take to get there. I just take the steps.