Eat your vegetables. Stand up straight. Chew with your mouth closed.
You say you already know all that stuff!? Peter states that he would never neglect mothering those entrusted to His charge. He would remind his children of what they already knew until either he or they both died.
Peter: 2 Peter 1:12 Therefore, I will always be ready to remind you of these things, even though you already know them, and have been established in the truth which is present with you.
We are not in danger of forgetting what we never knew. We are always in danger of forgetting what we do know. Never neglect and never despair of teaching the very basics of walking with God. It is the basic concepts and responsibilities that are soonest neglected and then lost in favor of spiritual novelties.
God: Isaiah 66:13 As one whom his mother comforts, so I will comfort you; And you will be comforted in Jerusalem.
Paul: 1 Thessalonians 2:7-8 But we proved to be gentle among you, as a nursing mother tenderly cares for her own children. Having so fond an affection for you, we were well-pleased to impart to you not only the gospel of God but also our own lives, because you had become very dear to us.
If you want to have impact on the lives of others, be like Peter, be like Paul, be like God. Take up the ministry of spiritual mothering.