We can tell that what Jesus is wanting to say is especially important in that He called the crowd and the disciples to Him. This part of Mark's Gospel is at the heart and centre of the Christian faith. Three facts stand out here:
1. The honesty of Jesus: here was a man who could balance the line perfectly between grace and truth! No one could say looking back that He had given them a rosy-eyed view of Christianity! He never offered an easy way to follow Him. Telling those who would follow Him that they would have to take up their cross to do so was saying that they must be ready to be regarded as criminals, even to die. Again, we know that in all likelihood, at least ten of the Twelve died as martyrs. Jesus came not to make life easy, but to challenge people to greatness.
2. Jesus never called anyone to do what He wasn't prepared to do or face Himself. Jesus is not a remote leader, sitting back and watching what plays out from a distance; He is with us, supporting, blessing and reaching out to pick us up again when we fall. We experience this in greater ways as we follow Him more whole-heartedly. Jesus has a right to call us to take up the cross, because He has done so Himself.
3. Jesus calls all who would follow Him to deny themselves, saying no to their self. Most of the time, what we want and what Jesus wants are different, sometimes in opposition, and it is a huge discipline to disregard our selfish desires and follow the King. I've often heard from someone who is seeking to follow Him in some new way, and sometimes that new way is a disguise for a way which they secretly fancy. I'm not saying that Christ does not give us 'the desires of our hearts', but we have to be very careful that we are not deceiving ourselves. Those I've met with often use Bible verses to back up their plans without due thought as to their context and plough along happily thinking that God would bless their crusade. We must train ourselves to say yes to Christ and no to self and the more we do that in our everyday lives, the easier it will be to take major decisions which are in accordance with His will.