How can we fear or doubt with promises like this?
8:26 "Likewise the Spirit also helps in our weaknesses. For we do not know what we should pray for as we ought, but the Spirit Himself makes intercession for us with groanings which cannot be uttered. 27 Now He who searches the hearts knows what the mind of the Spirit is, because He makes intercession for the saints according to the will of God."
Often people will tell me they don't know how to pray. I happily tell them they are right but it doesn't matter. Jesus has every detail covered. He knows we come to Him in such bad shape that not only are we not anything like the masterpiece we are meant to become but we don't even know where to start to get there. Like a drowning person that swims down thinking he is swimming up we are completely lost, confused, and disorientated. We try and pray away the very experiences God is taking us through to restore us simply because they are uncomfortable. Then we fret and doubt because our prayers are not being answered. All the while God looks past our fretting and doubts. He looks past our prayers even. He sees that in our hearts we want Him and He responds to that. Like a medical team God and Jesus and the Spirit work together to give us what we need not what we ask for.
So if you pray wrong or can't even find any words don't worry. They don't need our words. They have it all worked out. Help is on the way even when we never knew how to ask...