Many businesses that attempt to operate in a lean way tend to take the title "Lean" and try to operate their business with lean resources. If this occurs during or after running some lean manufacturing programs or kaizen events then the results will invariably a halt or even reversal of progress made through the lean initiatives - this is due to the overburden of labour resources. This can be equally detrimental in a manufacturing or office environment.
What does a lean business really look like?
A lean business is one that has or is in the process of identifying the following traits:
Every one of the above are important for the successful implementation of a sustainable lean program. Obviously not all will be in place fro the beginning, however without the last one it will be very difficult to attain most of the others.
So to sum up; obviously to even set the program in motion you will need management with some foresight, understanding and desire to achieve success through the implementation of a lean program. However if asked what is the single most important factor in achieving a successful & sustainable lean business, my answer would be "sufficient resources".
This answer is the opposite of the reality seen in so many businesses. So rather than reducing resources each time an efficiency gain is made (to make sure everyone is working 100 - 110% on their core role) change that mindset so your employees are working 80% on their core role and 20% on further lean initiatives.