How you live your walk of faith, how you choose to listen and obey (or disobey) God affects everyone in your world -- even people you do not know. I want to give you two extreme examples from scripture that show this principle.
Jonah was a prophet of God's. God told him to go to Ninevah and preach to that town. Jonah didn't like the Ninevites so he refused. He wanted them to go to hell. He boarded a ship that was going in a different direction. God wasn't phased. God told Jonah to do something and God intended to get him to do it. A great storm rose up. It was so large that the ship's sailors were afraid it would sink. They threw all their cargo overboard. That cost them a lot.
Jonah told them, "For I know on account of me this great storm has come upon you."
And he was right. He told them to throw him into the sea and it would stop. Those sailors didn't want to do that, but eventually they did and guess what -- the storm stopped.
Jonah's disobedience cost them all their cargo. Jonah's disobedience got them off course. Jonah's disobedience cost them energy and time and emotional strength.
If you flip to the book of Acts we see when obedience to God affects many in a positive way. Silas and Paul were in prison singing praises to God. They were in bad shape but praised God anyway. The other prisoners were listening. A miraculous earthquake hit "and all the doors were opened (in the prison), and everyone's chains were unfastened."
All the prisoners benefitted from Silas and Paul's obedience and faithfulness to their God. I gather that they were praising God trying to get through the situation for they had been beaten before being thrown in prison. Very likely they weren't even thinking about the other prisoners but their lives still affected their fellow prisoners.
So too for us. If we live lives in obedience to God, in relationship with Him, it will affect our worlds in positive ways. Maybe we think we aren't noticed. Maybe we think it just doesn't matter what we do when no one is looking, but it does. And we might not see how it could matter, but again, it does matter. We don't have to have all the answers. We just need to live a life for Jesus -- live in gratefulness and faithfulness and contentment. Those are the kind of lives that change eternity.