All people experience suffering. But, only a Christian experiences suffering because of self-sacrifice for the sake of God's kingdom. This suffering includes fasting, financial self-denial, and suffering so that others don't have to. It also includes feelings of agony in prayer as one intercedes for souls and pleads God's promises. But, the source of all these particular examples is that a true Christian has utterly given up his or her life to Jesus Christ.
Ultimately, suffering shows that we're serious about what God wants to accomplish. No advances are made in God's kingdom without the voluntary self-denial of men and women. So, we lay aside our natural life to live in the Spirit.
Is the suffering in your life merely that which happens to all people? Does it consume you so much that you don't have time or feeling left for Christ's kingdom? Or have you entered into the sufferings of Christ, that you may share in his glory?