3 John 1:3 For I rejoiced greatly, when the brethren came and testified of the truth that is in thee, even as thou walkest in the truth.
4 I have no greater joy than to hear that my children walk in truth.

We know John here is talking to his friend in Christ who people would tell him about of how he followed the the teachings John about being obedient to God. He was pleased to here of how his friend walked in the truth every day. Johns friend prospered in his soul and his daily walk bears out his faith in the truth. There is no greater joy than to know someone you have led to the Lord is walking in the salvation they received. Those who walk, or conduct, in the truth, or
belief, have integrity; there is no difference between professing and living them. We should hope that we could as good a teacher as John that people would talk to us about the lives we have affected or that we could tell people of the ones that lead us to Christ.