How are good business practices like losing weight?

Because the advice seems so simple and straightforward, yet is difficult to execute!

Want to lose weight? Eat sensibly, in moderation and exercise regularly.

Want to improve your business?
Develop a compelling vision, backed by a realistic, executable strategy. Translate the strategy into an operating plan, with clear milestones and expected outcomes which can be objectively measured. Assign the plan and responsibility to the right people and compensate them based upon their results. Sounds simple.

I just finished rereading four of my favorite business books; "Leading Change" by John Kotter, "Execution: The Discipline of getting Things Done", by Larry Bossidy, Ram Charan and Charles Buck, "Lean Thinking" by James P. Womack and "The Toyota Way" by Jeffrey Liker.

These books offer interesting insights into how some companies clearly outperform the competition.

What all the examples in these books have in common is that the founders or CEOs had a very strong vision with which, they were able to build a strong company culture (of process innovation, waste reduction, innovation, execution, employee development etc) that enabled them to compete very effectively over many years.

If every business leader were like the one's mentioned in these books, all American companies might be executing far better, but in reality, not every company is blessed with gifted leaders.

So the real question is; Is it possible to change a corporate culture from the middle? or must it always happen top down?