The Purpose of Prayer

I've always known that it's important to pray, & to pray according to God's will--& I have always prayed out of obedience. I have to admit, though, that I didn't quite understand why God commanded us to pray, knowing that He knows what we need better than we do, & also that He will do His will whether we ask Him or not. God is eternal & in control, & He has known exactly what He's going to do in every situation from way before we prayed for it. (I know that it's more complicated than that, because the Old Testament does talk about God changing His mind sometimes, but that's not the point...) I had thought that God wants us to ask Him to meet our needs even though He already knows them because He wants us to acknowledge our dependence on Him, & I think that's part of it. But I heard something John MacArthur said that I hadn't thought of from this perspective before: We pray because that makes us a part of what God does, & when we see an answered prayer we glorify God! I don't think we have the power to change God's mind or move Him to do something He wasn't going to do already-- He doesn't need us to ask Him before He can do what needs to be done-- but He commanded us to pray so that we can recognize that when our needs are met it's from Him, & so we will glorfy Him; that's what He created us for!