The KJV makes this more clear as a stand alone verse. It points out that “He” is the one who “keepeth” (guarding NASB) (5341). This is one of those simple truths that can make your day if you will let it.
We are not the moral police of our culture. I am not expected to fight every step of the way through life. By that I mean take a head-on, confrontational approach to the moral issues I must deal with. I don’t back down. I don’t compromise on truth, but it is not my place to think it all depends on me. The “He” in this verse is God.
We are to witness and speak up. A good summary of that comes from Peter
(1 Peter 3:15 KJV) But sanctify the Lord God in your hearts: and be ready always to give an answer to every man that asketh you a reason of the hope that is in you with meekness and fear:That should give you enough to do to keep you busy and be a high enough standard to make you feel guilty.
So? Relax. Prepare. Let God run the show.