I purposely commented on verse 13 before bringing your attention to verse. 12. Though today's verse speaks of something God wants you to do, verse 13 emphasizes how God will help you do it. Now, it must be clearly understood that Paul is not saying that anyone has to "work for their salvation!" No, but what he is saying is that believers are to live out their salvation or demonstrate what God has done in their lives. In other words Paul is saying you're saved - now live like it!!
Two very important elements are presented here. One is obedience. God expects us to obey what he wants us to do. Paul spoke about obeying him, Paul, that is. But he was obviously speaking as God's messenger when he said that. Now, as a Pastor, I don't like to tell people you have to do what I say. But I will say you must do what God says! Obedience is one of the hallmarks of a true Christian. You desire to obey the Lord because of all He did for you and because He knows what's best for you.
The other element is faith. God wants you to believe that what He says, He will do! In verse 13 Paul tells us that God is working in us giving us the desire and the power to do what pleases Him. Believe that God is actually wanting to do that in your life. He wouldn't tell you He would do something and not mean it! Now, again, there's so much more to say about this that I'll have to spread it out over the next bunch of Daily Verses. Stay tuned!