I consult with all sorts of companies looking to adopt elements of process and practice from the Agile/Lean offerings. Whether it's Scrum, Test-Driven Development, User Stories, Test Automation, Continuous Integration, Agile Estimation and Planning, Sprint Planning, or Sprint Retrospective facilitation, one challenge pervades across most scenarios. I have come to call it The Discipline Deficit.
A disheartening number of groups who take up a given Lean or Agile practice or process underestimate the amount of discipline required to master and sustain it. As a result, they either put forth a half-hearted effort and the attempt flops, or they get off to a good start only to abandon it. The unfortunate outcome of either of these scenarios is that the people who interact with said group are left with a rather bitter taste in their mouth, and as a result even the mention of the word Lean/Agile/Scrum/etc. becomes a trigger for painful memories and a general sense that whomever uses these terms is someone to be avoided.
I suppose this should not be a surprise; humans have a fairly poor track record when it comes to resisting promises of gaining something for nothing. There are more than enough opportunists out there selling Agile/Lean as a silver bullet of sorts that turns even the muddiest sow's ear into a gorgeous silk purse while requiring little to no effort beyond mimicking several steps and leaving the existing culture intact, no matter how dysfunctional it may be.
So, once again let me declare that Agile/Lean practices and processes are neither substitute nor remedy for hard work, but rather effective vehicles for structuring and managing hard work. They are also wonderful tools for thinking about the way a group works and its culture, providing information that can be used to improve it - once more through hard work. If you are going to give any of these things a try, consider the cost both in effort and cultural impact. There is no shame in deciding not to apply them; in some cases it actually reflects wisdom and maturity.