We know that all things work for good for those who love God,who are called according to his purpose. For those he foreknew he also predestinedto be conformed to the image of his Son,so that he might be the firstbornamong many brothers and sisters.And those he predestined he also called;and those he called he also justified;and those he justified he also glorified.It is a big promise. All things work for the good of those who love God. I love God. So all things work for my good. Sweet! Yet we need to be careful. What is meant by "good" here? The rest of the passage makes that clear. Being conformed to the image of Jesus. That is the good that is being referred to.
God knew beforehand who would respond positively to the gospel. He took that knowledge and used it to accomplish something called predestination. That is a word Calvinists use a lot. When they use it they refer to a doctrine that Catholics reject. That does not mean Catholic reject predestination completely. As you can see in this passage, the word is in the bible. We have to have some understanding of what St Paul meant when he used it.
What this means is that God uses Hid foreknowledge and power to plan our road to holiness. It does not mean it will be easy. That is often the implication when people quote the text. That all of life will be good because we are believers and that means we will have great jobs and wonderful relationships and good health. All of life will be good and that means we will become more and more Christlike. Of course, Christ did not have an easy life. So it is good news. It means we don't just go through life and put in time until heaven. That God is actively working not just in us but in everything and everyone around us.
His goal is to bring about the virtues of faith, hope and love. Being called is to hear God's voice and respond positively to it. That is to have faith. Being justified is to understand God's mercy and to have the hope of heaven. Being glorified is to let the grace of God permeate the depths of your being and to make you a lover through and through.
We tend to comb the scriptures for assurance that God will protect us from some of the things we worry about. The trouble is we don't know God's plan. He might be protecting us from all manner of misfortune. That is often the way He works for our good. Yet there are no guarantees. He might let the calamity we most fear happen. That is hard to face. We know the future is planned for our good but we don't know what that good looks like.
The other aspect of it is our choice. God can give you opportunities to grow in holiness and you might not take them. God can put someone in your life who is difficult for you to love. That is a great chance for you to become a better lover. Yet you can respond the other way. You can treat them badly. God is working for your good and you are turning it into something bad. At the end of the day grace always requires our cooperation.