At times in life we suffer because we do not trust God. This or that happens to us and we worry about the future. It can be in a sense that our worry in these times if we look back was the primary suffering we faced.
It is easy for us not to trust God's goodness toward us. Jesus in his preaching tells his followers not to worry about the future because each day has enough troubles of its own.
It is not uncommon for our lack of faith to cause us suffering as at many times we suffer simply because of worry. It is not that the hardship is brought on by our lack of faith, but rather our lack of faith makes the hardship ten times harder than it really is.
God wishes us to be happy and that is why Jesus had many things to say about worry. It is easy to feel that God is not for us, but you see everywhere that God is for us.
God wishes for us to enter the kingdom. He reaches out to us to join him for eternity. He does not want us to worry in the present day. He wishes to bring him our troubles in prayer.
If God is for us who can be against us. God is for us at all times. He loves us even when we find ourselves difficult to love.