a. Sometimes suffering makes a necessary good possible. If God eliminated that suffering, the corresponding good also would be eliminated.
b. Suffering can bring us closer to what is right and draw us away from obstacles to achieving happiness. Only when we are weak do many of us rely on God and explicitly repudiate our divine ambitions.
a. The suffering that we may experience in our life can be the way to our better future. God is preparing us so that if big trouble happens, you'll trust Him and you will pass that big trouble.