Well sadly, it is easy to feel this way sometimes. And there may in fact be times throughout your life where you will go through difficult times. James tells us in James 1:2 to "Count it all joy when we face trials..." A great example of somebody who was able to do this was Joseph. He was somebody who faced so many difficult times but never gave into self pity or to bitterness. When somebody wrongs us, how hard is it not to feel sorry for ourselves and bitter towards that person? And that is something that Joseph never felt.
In dealing with adversity, there are 3 P's that we need to remember:
1. The Promises of God. God's promises will give us the hope we need to cope with our adversity. Phil. 4:13 says, "I can do all things through Christ who strengthens me." With Christ, we have the strength to get through any trial.
2 . The Plan of God. Even though we sometimes don't see an immediate result, God is working for us. He is on our side and wants to see us succeed. Romans 8:28 says, "We know that for those who love God all things work together for good..."
3. The People of God. Even though we sometimes feel like we're the only ones dealing with something - odds are we're not. We need to comfort our fellow Christians to help them deal with their adversity. Paul says in 2 Cor. 1:3-4, "Blessed be the God and Father of our Lord Jesus Christ... who comforts us in all our afflictions so that we may be able to comfort those who are in any affliction, with the comfort with which we ourselves are comforted by God."
It's always easiest to take self pity on ourselves and feel bitter toward somebody else - but this is not what the Lord wants us to do. He's on our side and is wanting to help us through our afflictions.