Although not completely physiologically correct there is a useful Left Brain/Right Brain model that we can use. The left side of our brains is logical, linear and provides filtering of ideas, so although it will provide solutions it also has a nasty habit of saying 'but it won't work', 'that is not a good idea' or 'the boss will not be happy'.
The right hand side of our brains is linked to creative behaviour and does not have these filters thus increasing the range of possibilities. The problem is, how on earth do we hand our problem to one and not the other? Simple, we play tricks on it!