Some believers think that your personality is stripped of its sinful nature and it is rendered in its natural 'prefall' type state. Mental illnesses are caused by the brain - so all of those would be gone. All that would be left is the part that loves God and you spend all your days wandering around a city made of gold worshipping Yahweh for eternity.
I might once have felt it prudent to keep silence, for I perceive that the race of men, while sheep in credulity, are wolves for conformity; but just now, happily, in this breathing-spell of toleration, there are so many varieties of belief that even an unbeliever may speak out.
--Carl Van Doren, 1926
™ Version 4.2