Visualizing the neck horizontally is vital to avoid getting stuck playing in a box (or in one position on the neck).
Instead of learning the A minor pentatonic at the 5th fret (low E) and going down the strings at that spot, try playing it
only on that string. Continue to do that for each string. Practice this daily until you become comfortable with it.
Now, when you go to do a simple improvised solo you can move up and down the neck, instead of staying in one spot.
You can use this for a guide: http://www.tonart.com/Main/ScaleLessons/pics/ampent.gif