Jesus appointed twelve, whom he also named apostles, to be with him... (Mark 3:14)

I was talking to a friend recently who was telling me something of what Jesus has been doing in his life in recent years.

It was, he said, as though he had been "re-formatted". In other words, Christ had been so thoroughly at work in him that he felt he was being completely re-worked from the inside out.

My friend – who is a church minister – shared that sometimes he spends whole days in prayer and reading the Bible. And he then went on to wonder aloud about his pattern of work, and how the re-formatting he has experienced on the inside might in turn re-shape how he pastors the congregation he serves.

I found what he said both refreshing and challenging. For surely his is the sort of journey which should be part of all Christians' experience if we are truly being re-fashioned into God's image "from one degree of glory to another" as Paul puts it (2 Corinthians 3:18).

Not all of us are church ministers who can spend whole days in prayer and Bible-reading, of course. And yet all believers should know something of the transforming power of Christ at work. How can this increasingly true for us?

As we continue our walk through Mark's Gospel we reach the section where Jesus appoints a dozen of his friends as apostles (Mark 3:14). And there is a little-noticed phrase used by Mark which is actually the key to what is going on. Indeed, it is something vital which lies right at the heart of what it means to be a disciple.

Of course, we don't have apostles in quite the same sense today. Those twelve were unique both as witnesses to the ministry and resurrection of Christ, and in the authority of the writings – the New Testament – that they bequeathed to the church.

But the first thing he calls them to is something that all disciples of Jesus, including ourselves, are called to emulate. And that is simply, as Mark puts it, before anything else, "to be with him".

The phrase is more than a throwaway line – it is a very significant one. Later on, as the Gospel takes Jerusalem by storm, some of those looking on were astonished by the courage of Peter and John. And yet they could see what had made all the difference: "They took note that these men had been with Jesus," (Acts 4:13).

What does that mean for us? Preaching recently, the Bishop of Jarrow, Mark Bryant, said: "Mark tells us that Jesus appoints twelve disciples 'that they should be with him'. Jesus' greatest longing and desire is that we should be with him in order to follow him. I think we have to learn to be intentional about that."

It's always good to be reminded of some of the basic elements of being with Jesus: reading God's Word regularly – and perhaps we need to find some new Bible notes to help us (see for example www.thegoodbook.co.uk); prayer – and perhaps our prayer life needs re-invigorating (a book such as A Praying Life by Paul E Miller may help); being part of a church family.

But it starts in our hearts. As one prayer puts it: "How well I know, Lord Jesus, that doing noble things for you is not the same thing as spending life-giving time with you. Thinking great thoughts about you is not the same thing as vital communion with you. Helping others understand the gospel is not the same thing as drinking presently and deeply from the wellspring of grace for myself."

Why not read the full prayer here and make it your own right now?

David Baker is a former daily newspaper journalist now working as an Anglican minister in Sussex.The Rough Guide to Discipleship is a fortnightly devotional series.