Heaven is at hand, within reach; it's where God dwells. It's a realm, not so much a place.
I would have thought you might go with Luke 17:21, "Neither shall they say, Lo here! or, lo there! for, behold, the kingdom of God is within you."
I could answer two ways: Spiritually and Physically. Spiritually, I couldn't tell you exactly where it is. Physically, I can tell you I only find it about once a week when my wife feels like showing it to me ;-) Crass, but true. I like telling my wife: "God created it; I celebrate it."
I hope heaven is better than sex, because otherwise heaven will make you pretty sore after just a few hours. I wonder if that means hell is full of couples who have to use a condom...
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