I think what most people are describing is when they are full of the Holy Ghost.... maybe.
That is what I feel like WHOLE, complete. Like I could fly. Like, "It is joy unspeakable, and full of glory, or the half has never yet been told." I felt literally a fire inside of me. Sometimes, I've heard His voice. I hear it more, when I talk to Him more. I have conversations like He is there with me. It's a clear as day... although... not audible. The last thing I heard Him say, "Why do you doubt? Why are you so sad? Do you think for a moment that I lost control of the situation? Do you think I wasn't there? I said I'd never leave you. I never will. No matter what you do. Even if you sinned against me. You said you were sorry, and I forgave you. You brought it up again not I. I am God, I will not forget you."
Once I was having a nightmare... I've had them since I was little. Once, He appeared around me as a shield... and the monsters vanished.
I also feel free. Love... complete unselfishness. And such joy... this Earth could not contain the joy. If only the lost could feel that... they'd never again doubt God, or what was the truth. There's nothing like it, not in this Earth. It's not the joy of doing for others, it not the joy of self sacrifice... it's nothing at all like any of the pleasures one can enjoy. I know everyone feels like they are searching for something. "The pursuit of happiness". Well I've found it... and I'll never search again! I just tell people "THIS IS IT!" That is the only words that come to mind. It's "IT". Jesus says, that we will never thirst again! But I didn't know that until later. I think as the hymnist wrote, "My heart has been singing since that day." He loves me unlike anything on this earth, and I LOVE Him too!