I suppose that the hardest part is accepting criticism.  As an assistant dean, part of my job is guiding my teachers through both the training and the implementation.  I've had more than my share of teachers who tell me what great ideas are found in trainings -- but who go right back to the same old thing because it's easier.  it's not much esaier for me, I'm just as human as the next person.  I've found that, every now and again, the best way to force myself to implement what I've learned is to hit the delete button and get rid of previous lectures and evaluations. This forces me to revamp the class and use what I've learned.