Bible scriptures on how to walk in the truth

How do you walk in the truth? What is the the truth and how does the Bible define walking in the truth?

2 John 4-It has given me great joy to find some of your children walking in the truth, just as the Father commanded us.

1. Obeying the commandments of God
2. Obeying the laws of your country as long as they are not contrary to the Bible
3. Obeying the rules of your office that are not contrary to the Bible
4. Following the dictates of your conscience
5. Avoiding lies