Before thinking about what discipleship is its worth taking some time to think about what it isn't. I think very often we make wrong assumptions. Discipleship is more than just bible teaching so being in church and hearing the bible taught does not automatically mean that we are being discipled. It can mean we are being discipled but just being present and listening does not automatically mean we are being discipled. Neither does being in a home group, or whatever you call it, or attending a gospel exploration course, all of these things have the potential to facilitate and aid in making disciples that last but are not discipling in and of themselves.
Nor are Christian friendships, we can have friends who are Christians but who are not discipling us or whom we are not discipling, why? Because there is no intentionality in the relationship - in fact the only thing that makes it any different from any other friendship is the backdrop of church in which we meet or the fact that what led us to meet in the first place was our commonality in the gospel rather than in loving golf or dogs or tiddlywinks.
Lastly even 1-2-1 bible study is not discipleship in and of itself. Again it may be a helpful part of discipling someone but discipleship is much more than just studying the bible together. I think this is perhaps the one we most often default into thinking of as discipling others. Indeed you sometimes here of people discussing doing a 1-2-1 bible study as discipling someone, it is not unless there is more to it than reading and talking about the bible together and praying.
Until we get rid of these wrong understandings of what discipleship means we will never fully engage in discipleship. We will settle for an almost discipleship rather than the real full blooded thing. Discipleship is not automatic, these things all help in discipleship if we use them as part of our discipling others rather than mistakenly thinking they are our discipling of others.