I used to say that the most important ingredient in a formal learning program is motivation of the students. Having poured through thousands of results of recent big skills programs, I think the most important ingredient is the honesty of the students.
Honesty is the genuine awareness of strengths and weaknesses, and then the impact of their strengths and weaknesses.
I have also found that honesty and sense of humor can go hand in hand. While not all people with a sense of humor have honesty, almost everyone who is honest has a great sense of humor.
I have also found that some cultures crush honesty. Some cultures pounce on any sign of weakness. Some people and groups are defensive. These cultures tend to evolve and grow the least, although they get stuff done in the short term.
Any individual and organization should, by the way, balance introspection and action. But any training program of big skills requires that kernel of honesty.