The key to understanding this difficult passage is to understand the "journey" that Christ is on.
None of us is able to make the journey with him of for him, and that's the point.
This is Christ's journey, and only he can make it. That's what makes him our Savior.
He walked the path for us, and when He was done he laid down his life for us and on the third day he rose again. And upon rising, he declared us his perfect disciples.
Ultimately, the cost of discipleship is not what we pay. It’s what Christ has paid for us.