So far her challenges have been:
Focus. It's short. And she is easily distracted by "shiny" things.
I don't want to. Already! So young to have these moments. But she is a terrier. So we play the i-know-you-don't-want-to-but-CAN-you games. And she is improving each session. I haven't been brave enough to see if it's working yet. When she throws the "I don't want to" in my face during a training session or real life we just end the game and I play with someone else. Soon I'll see if the training is paying...
And that's it challenge wise! She is highly motivated and loves to be right. So it's super fun to train her. I'll try and video some trainingn sessions to post here so I can look back and say "LOOK!"