If you limit yourself to just those lines, there's only a limited amount you can conclude, and must of that is by implication. The translated meaning of those lines indicates that the speaker values the Lord's joys more than a brief and dead life on earth. That would mean that while life on earth is fleeting, life in Heaven is not--it is everlasting. Since the speaker says life on earth is "dead," this establishes a paradoxical opposition. Life is death, which means that the time after death is life, or is real life. To put that more directly, heaven is the true life. And when the speaker refers to heat, that means that he is more passionate about the afterlife than he is about life here on earth. His earthly life is comparatively passionless.