Do you know why we say this?  Because you may not like what you get when you get it!  What if you choose the wrong "goal" to aim for and you achieve it,  only to be disappointed in the fact that the goal you had selected wasn't exactly what you wanted after all.  What you really wanted may have been within in easy reach, you just weren't looking...and let it slip through your fingers.  This is why identifying this ONE key is crucial to your success.