Likewise the Spirit helps us in our weakness. For we do not know what to pray for as we ought, but the Spirit himself intercedes for us with groanings too deep for words. And he who searches hearts knows what is the mind of the Spirit, because the Spirit intercedes for the saints according to the will of God.--Romans 8:26-27 (ESV)
Do you feel weak right now? The Bible says that right now, no matter how strong you feel, you are weak. How are we weak? There are many ways in which we are weak. Perhaps right now, you have the cold that is going around and your body is weak. Maybe your mind is weak (mine is). One example of our weakness which Paul mentions in this passage is that we do not know what to pray for. We are dense (I know I am). We are unobservant--we miss obvious needs in our lives. Our minds are fallen and so we fail to pray as we ought.
But, in our weakness the Spirit helps us. Isn't that amazing? When I am weak, God Himself gives me His power. Now, I believe we should interpret verse 26 widely. Paul does not tell us the only way the Spirit helps us in this passage; he simply gives an very important example. One example I could give would be: When I wake up in the morning, one of my first prayers is, "God, help me to get out of bed and wake up." God is gracious; when I pray this prayer I almost invariably feel energized and ready to wake up. This is just one of the ways the Spirit helps me in my weakness.
We need to realize that as children of God, indwelt by the Holy Spirit, we have God's power promised to us. This afternoon, I was having some difficulty dwelling on the Lord and His gifts to me. However, after I cried out to God for help, I found it far easier to think on the Cross. I need to think on this fact all the time: The Spirit of the Lord God helps me when I am weak.