Life is both a series of choices and opportunities. This is why it is so hard to answer the question, "where do you see yourself in five years?"
The question itself is flawed. A better question is, "what goals have you set for yourself that you want in the next five years?"
Some will ask, "how can I set five year goals?" The easy answer is, what do you want that will take more time to achieve?
One of Ben Franklin's 13 Virtues was Resolution. "Resolve to perform what you ought. Perform without fail what you resolve." - Ben Franklin
Goal setting is as much planning as it is having the character to "perform without fail what you resolve." Persuing goals, both big and small, was Ben Franklin's legacy and it took him a lifetime to achieve them.
We should know where we want to be in 1, 5, and 10 years because we have set meaningful goals. If you don't, then you'll never know where you're going.