Ask any mature Christian what they have gone through and you will understand why Jesus said in John 16:33 that in this world we will have trouble. It is not just believers but everyone goes through trouble. God never promised a life without trouble. Look at the life of Jesus, the apostles, the disciples, the prophets and even the children of Israel. Trouble is the lot of man but, Jesus said to be of good cheer as He has overcome the world.
What is important is to go through everything with Him as He is always there to help and guide us