II Tim. 1:14 With the help of the Holy Spirit who lives within us, carefully guard what has been entrusted to you.
We can't do it alone. We need the Spirit's help if we are going to effectively protect that which God has revealed and given to us. Left alone, our sinful nature will take that which we have and cause us to misuse or abuse it. We are easily influenced by our sinfulness and must not ever think we don't need God's help at keeping ourselves pure in thought and deed.
The Spirit lives in every believer, but I wonder just how much we allow the Spirit to really live in us. What the Spirit is capable of doing and producing is amazing. We limit His work in us. His work includes pointing us to Christ, presenting truth in a way we can understand, producing fruit in us that others can see, and putting gifts in each of us so that we can serve the Lord more effectively. The Spirit gives us all the resources we need to live holy and productive lives before God.
We must not take for granted His presence and power. We must let Him work freely in us and with His help protect that which has been entrusted to us. No matter how far along you are in faith, make it a priority in your life to cooperate with the Spirit as He works in you to make you a workman that does not need to be ashamed. Let Him change you and lead you into godliness so that you will be a servant whom the Lord can say, "Well done, with you I am well-pleased."
He who fails to carefully guard his walk with the Lord and all that is entrusted to him will soon fall into sin.