What do you think heaven is? A place in the clouds where the good people go to play harps? A more accurate description would be to simply say that heaven is the home of God. It is where He is, and He is not in some distant place light years away. Jesus says the kingdom of heaven is near, it is at hand, in your midst. Do you not know that your bodies are temples of the Holy Spirit? Yes, God dwells within you. The saints and the mystics have always proclaimed this. St. Teresa of Avila said the soul was like castle with many mansions. In the inmost mansion, at the center of the castle is God. He is there in your heart waiting for you to discover Him. That means that the heart is heaven. In the fourteenth chapter of his letter to the Romans, Paul says the kingdom of God is of righteousness, peace, and joy in the Holy Spirit. He is with you know, inside you in the very core of your being, sustaining you and loving you. All we have to do is recognize His presence and live our lives out of that power. The way to do that is simple. It is prayer.
St. Teresa said that prayer was the entrance into the soul. St. Terese the little flower said that prayer was a gentle lifting of the heart to God. I think an easier way of saying it is that prayer is your relationship with God. There are many methods of prayer. Vocal prayer where you talk to do. Mental prayer, or meditation, where you listen to God. Contemplative prayer where you are simply quiet with God. It can be actions as well such as in the way you deal with people and things. Your relationship with God deals with not just how you deal with Him, but in how you deal with all His children and the world He made. In this way your whole life will become prayer. This is the righteousness that Paul meant, and with it comes great peace and great joy. You will have entered the kingdom of heaven now and in this life.