Count it all joy my brothers, when you meet trials of various kinds. For you know that the testing of your faith produces steadfastness. And let steadfastness have its full affect that you may be perfect and complete, lacking in nothing.
In this passage we see that in every moment of trial and suffering God is offering us joy. And not only is He offering it to us, but He actually commands us to have it (as in other places like Psalm 100). But how can we take joy in trials and suffering?
We can count it all joy when we meet trials of various kinds because these trials bring us the prospect of spiritual growth. Think about it in this way: If someone wants to be the best runner ever to be seen on the face of the earth, what would he do to prepare himself? He would push himself to the limits. Yes, running while exhausted isn't exactly a pleasant experience, but he knows that even though it's painful, it's training him to be a better runner. He can take joy even in those painful moments because he knows the great reward that comes with it.
Now consider the Christian life: we should consider no price too high to pay if we could only get one step closer to our Savior. Great qualities don't arise from comfortable, easy lives; they come from hard, rigid lives plagued with difficulty. The blessings of victory doesn't come to those who never fight; they comes to those who through many painful battles have been brought to triumph over the enemy. We can't suppose to be valiant warriors for the Kingdom of Heaven without embracing trials of various kinds; we can only be victorious in this war if we're reminded that this isn't our home. We should recognize that when God brings upon us trials and difficulties, He is lifting us not, not pulling us down.
For the Christian, joy is a decision; we have every ground on which to rejoice if we so chose to do. So when we meet trials of various kinds, let us not lose our joy, let us abide in it all the more, for God is providing us with a means by which to draw closer to Him. Yes, let us count it all joy when we meet trials of various kinds, that we may be perfect and complete, lacking in nothing, for we know that the steadfastness and patience that comes only through trials will sanctify us, and ultimately bring us closer to God.