You assume an awfull lot there. It's not like you could feel anything while you aren't even a single living cell. If you were stuck on earth the whole immortality deal would probably already cease to be an issue once the sun goes super nova, since being turned to plasma would most definitely prevent you from being concious, let alone feel a thing. If we talk about immortality by regenerating, then where does the energy/matter for that come from?
At that point it really boils down to how you are going to explain the mysticism behind your immortality in an obvious scientfic universe. How would this true immortality work? What would be the limits? Are there limits? Is it of supernatural origin? Can you obtain other supernatural powers or access to a supernatural world? That train of thought in near endless.
Just as bit of a thought provoker: Even if you are truly immortal in the widest sense for the past 1 million years, what would happen if you are caught by a primitive tribe? What if they turned you into a never ending supply of food? There is alot of shit that could happen to you over the span of a million years (a single one is enough usually..) that could turn all that time into a constant living nightmare, even if you are guaranteed to survive until you reach "today" again. It also poses the question of how your (continued) existence would break this world.