How do you successfully adopt TDD in an organization? Training alone is not enough in my opinion as I feel it requires a change in process and mindset. If TDD has been implemented in your organization can you provide what steps/approach were taken to successfully implemented.
Same way a group of humans successfully adopts anything long term.
Each individual values it.
Remember that developers are knowledge workers, we value things which make knowledge easier to work with. Demonstrate how 'this new thing' does that.
Just demonstrate it in such a way that does not come across as condescending. Knowledge workers will get out of joint if you dictate, or otherwise inform them that they are 'stupid'.
Also knowledge workers may apply the brakes for other reasons. One being that knowledge work requires agreements between many people on how knowledge is shared and updated. Changing those agreements too quickly will cause issues, so don't just assume that resistance is because of arrogance.
That being said if those agreements and the bureaucracy around them is there just for structures sake. You might need to actively deal with it (preferably by removal, but at-least lightening it).
Above all else you have to provide Leadership and Support. Leadership to give direction, but not force. Support to assist adopters through the rocky parts, but not to treat them like babies.
My experience is that it must start with buy-in from management. First complaint I hear when trying to introduce TDD is "Well, our management doesnt' want us spend time on tests." Thus, I believe the first step would be to get management send clear message that long-term benefits of TDD outweight short-term effort in implementing the tests.
The next step would then be encouraging engineers to adopt different workflows and patterns of work, that enable TDD. This is long-term effort that needs skilled mentors and coaches to work with developers on daily basis. It is not cheap or fast. But if management sees value in TDD, they will also see value in spending so much time and effort in actually teaching efficient habits to engineers.