Andrew was a well-respected senior pastor at a highly esteemed church of 2,500. But when I met him, he had just decided to leave his position. At the time, he didn't have another job offer and wasn't sure what he was going to do next. But he realized he was not the leader his church needed for the next stage in its lifespan.

"I used to say my next stop will be my last one," Andrew told me, "but I just don't say that anymore, because I no longer think I'm supposed to stay in one place forever."

Andrew had come to a realization that I have been observing over the last few years: some leaders have a shelf life.

The old paradigm assumed that a pastor should ideally make a commitment to the church 'til death do them part. But I don't believe that is realistic or ideal in today's culture. In fact, many churches would be better served to realize that it's perfectly acceptable that some leaders' effectiveness will expire after a certain point.

The office of pastor requires not just shepherding and ...