How do you define spiritual formation?

The reason I am writing you is because I am trying to better understand what spiritual formation is for me and for the Wesleyan church, and in this search I think it is important to seek the wisdom of today's leaders. I have heard a lot on this subject from people such as Richard Foster and Dallas Willard, but I was wondering what Spiritual Formation is to you. How would you define Spiritual Formation and what kind of importance would you place on it with the current generation? I appreciate your time.

I hope to do some writing on this subject in a year or two. In the meantime, I have deep appreciation for what my friend Dallas Willard is saying. He, and those he points to, are great guides.