One of the theories of the afterlife that seems to make a great deal of sense is that it is the hallucinations of your brain as it dies. Much like dreams, your brain would tell your consciousness all sorts of outrageous lies, and like dreams, they would seem to last far longer than they would in real time. Hence, you would exist forever in the hallucinations of your brain.
If, for sake of example, we accept that the above theory is true, it brings up some interesting consequences.
Picture, if you will, dying of illness in a bed. As your dreams take cues from what happened to you that day, so would your brain take cues from your surroundings as you die, sending you into a world based around that of your surroundings. If you died of illness in a bed, your hallucinations would naturally continue in that vein, for all of your consciousness's eternity.
Conversely, if you died in a battle, your brain would be intoxicated with a cocktail of adrenaline, endorphins, and the exhilaration of comb