Two of us in here

In the 1960s Roger W Sperry discovered that the brain has at least two very different " thinking modes".  Brains are made up of two hemispheres connected by the corpus callosum.  The left-hand side - which actually controls the right side of your body  - tends to deal with number, logic, language and structure.  The right-hand side - which controls the left side of your body - handles things holistically, and specializes in imagery, colours, and spatial and musical awareness, amongst other functions.  This specialization is a general pattern, and may be stronger or weaker or even reversed in some instances.  Overall, there is a lot of evidence for this specialization: understanding this bicameral mind allows us to make better use of our brains.

Left brain thinking tends to be convergent, that is, looking to narrow down and focus on the answer.  Right brain thinking is more divergent, looking for connections and expansions from the starting point.  Each has its place, but the currently dominant human cultures rely very heavily on written and spoken communication, and on logical and structured approaches.  This places a great emphasis on left brain thinking, and tends to reward those whose natural bias is to think in this way.  That approach has been phenomenally successful in many ways, and in particular allows for coordination on a grand scale.  However, it is not without its problems.  In particular, left brain thinking can be very constrained and inflexible when facing new or complex situations.

The cultural emphasis on the left brain thinking means that many practical creativity techniques are ways to reawaken and use the right brain.  If you're naturally a right brain thinker then you may need less help with this, and more in developing structured approaches and convergent thinking.  If you are left brain thinker, then developing your right brain skills may be challenging - but probably worth it.

The creative problem-solving model was first developed by Alex Osborne in the 1940s and 50s.  It relies on managed cycles of divergent and convergent thinking - in other words, switching between the left and the right brain modes.  A lot of the challenge in doing this successfully lies in getting the left brain to relax enough to give the right brain space to work.