In 1 Pet 4:13, Peter gives message where he urges his readers to rejoice in their suffering for Jesus Christ.  The Lord never promised that everything in life would go smooth.  In fact as a Christian it can be quite the opposite.  The lesson we can learn from this verse is that when things happen that are not top good we should rejoice.  Joy is that deep seated contentment where you know everything is going to work out.  Paul writes in Rom 8:28, that all things work together for good.  That does not mean all things are good but all things work together for good.  You may not see the purpose at the time but when you trust God and rejoice your attitude towards it changes.  Our perspective and attitude towards something is the secret to defeat or victory.  When you choose to trust God and look at things from His perspective it changes everything.  You say things such, "God I trust you."  "You have everything under control."  When you know God no matter what happens you will not panic because you have observed God’s faithfulness in the past and you know He will be faithful now.  So today rejoice in whatever you are going through and see the goodness of God.