Take another step.
The instructions: a journey of a 1000 feet begins with a single step tell how to reduce the size of the problem. The problem is how to cross the parking lot. After taking a single step, the problem is slightly smaller.
Of course, now you reduce the size of the new problem by taking yet another step. Keep doing this. Before long, the problem has been reduced to the size of a single step.
Now, take the last step.
How do you know when the "cross the parking lot" problem has been solved?