This Sunday we celebrate the Ascension of Jesus Christ into Heaven. It seems strange that we would celebrate Jesus leaving this world. However, Jesus tells us that He has to leave so that the Holy Spirit can guide us from the inside out. It as though Jesus is taking off the training wheels so that we can be full participants in helping in His ministry of saving souls.
In this time between Ascension and Pentecost, we will be waiting to be infused with the Holy Spirit. The apostles must have been wondering: "What will the Holy Spirit be like? How will we recognize Him? What will the Holy Spirit do?"
We know some things about the Holy Spirit from His description. He is holy which means he is different than us. So when we receive Him, we will be different. We will be aware of something new happening within us. We will be surprised. He is also Spirit, which means He is invisible and immaterial. He can therefore enter into us and dwell in our hearts.
You can tell you are listening to the Holy Spirit within you when you are surprised by thoughts and feelings that encourage, give a greater knowledge or understanding, provide wisdom, help find the right words to counsel a friend, or just grow in piety and be drawn into a greater wonder of God. If these are things you desire, ask to receive the Holy Spirit and you will receive the same gifts the apostles received 2000 years ago.