I believe we as humans by nature feel a need to advance ourselves; we like learning, discovering, and making things that make our lives more comfortable and luxurious here on Earth. We like being taught by those who came before us, adding to what we've learned, and then passing our knowledge to future generations who will then add to what we've taught them.
But what about those who believe they will go to Heaven upon death; where everything is perfect, no advancing, no discovering, no ancestors to gain wisdom and knowledge from, no children to raise teach and pass our knowledge to, just spending eternity sitting around God telling him how good he is, how long before that gets old? Could they truly be happy under those conditions?
It seems to me when they get to heaven they would have to have the mentality of a pet or a slave in order to be happy in Heaven for eternity; what do you think?