Did you know that if you stand at the North Pole, there is only one way to go: South?
If you stand at the very top of the earth, it is not possible to go North, because you are already at the northernmost point of the earth. You can't go East or West either, because since the pole is only a point you'd walk right off earth, and there's no direction in space technically you won't be going anywhere. So the only direction left is Down (a.k.a. South). Once you've stepped (even if it's a milimetre) closer to South you'd be able to go East or West.
Basically whenever you go in a direction you're going in a circle (if you walk in a straight line from the south pole to the north pole, that's half a circle. Then if you go back to the south pole it'll be a full circle. Get it?). It's just that some of the circles are bigger than others. Eg. If you are one meter away from the north pole and go from East to West your circle will be very small since you're only one meter away. By contrast, if you go from East to West on the Equator, your circle will be huge.
Hope that made sense. It helps if you have a picture to look at while you're reading this. The same applies to the South Pole.
