How Do I Limit The Movement Of The Player?

Hi.

I have been trying for weeks now to figure this out, I have researched and tried everything I can think of to figure this out. I feel this is such an easy issue to solve but I cannot figure it out.

How do I limit / restrict the moment of a character?
For example:



I want the player to be able to only move:
*UP/DOWN
*LEFT/RIGHT.

How do I do this?

Thank you.

 

Figured it out -_- finally!
Can NOT believe how stupidly simple it was .... -_- I was thinking way to advance -_-

 

@Shrek you should post your solution even if it was easy