God has the ability to manage every aspect of our lives, even the trials that we face, and make them work together for good. He works all things, not some things and He works them together for good. The promise is given specifically to those who love God. He manages all that goes on in our lives because we are called according to His purpose.
I very rarely remember this verse when going through trials. It’s not until a brother comes to me and tells me not to worry. I have to remind myself that God will work it out for good because I have been called according to His purpose. There is a reason and purpose for why I’m going through this trial. God knows that reason and purpose.