To initiate intentional discipleship into an existing relationship that is not intentional about discipleship, I suggest you introduce a level of intentionality to your friendship, remaining relational but seeking to be purposeful. I did this last week with a friend who is also an emerging leader... I invited him out for coffee to a local coffee shop, and we caught up on personal news and how we are each doing. As we talked, I looked for areas to encourage and affirm him, which was easy and natural to do. Then I lead into a discussion about a key topic pertaining to his leadership development. I asked a couple questions that I wanted to stimulate his thinking and add some intentionality to our relationship, albeit very low key at this point.
At the end of the conversation, I suggested we get together again in a few weeks. He was very warm to the idea. I will suggest at that time we meet "regularly" to build our relationship and encourage each other. I don't mind if a person sees our time together as peer mentoring... I let the description be determined by the person so long as we are investing in one another intentionally. If a person seeks to disciple me and it is appropriate, I would receive their input, no matter their maturity level, as I believe good discipling always involves a degree of reciprocity, and humility is always good for the soul.