Firstly, since your body / brain goes nowhere post your demise, you'd need to demonstrate actual mind / body duality - an immaterial something that's part of you (i.e. - soul, essence, spirit, personality, whatever) that still exists (if it can be said that something immaterial or non-physical actually has existence) post your kickin' the bucket. Considering that you weren't conceived with anything non-physical, you'd need to explain where in fact your non-physicality bits came from. Further, all immaterial or non-physical concepts only can come into actual 'existence' when consciously thought about or subconsciously stored in memory. Both thought and memory are purely physical processes.
The main problem I have is that the immaterial part of you - your soul, etc. - has no sensory apparatus (eyes, ears, nerves, taste buds, etc.) and no brain to process any sensory data. Therefore, in the afterlife you would be deaf, blind, etc. How does your soul actually experience the external reality that you inhabit in your afterlife?
But there are two other problems. The first is that 'eternal' bit. An eternal afterlife sounds nice until you realize you'd outlast the Heat Death of the Universe, trillions of years hence. If you get bored on a weekend afternoon, imagine trillions upon trillions of them. The question is, how can you fill in that time without going stir-crazy with boredom hundreds of times worse than anything you've ever experienced before?
The second problem is more significant. Since that you that is you changes from day-to-day, which version of you is that you that gets the afterlife? Changes in you are not just physical in that old cells die, new cells form; atoms come, atoms go; you put on weight, you lose weight; you change hairstyles or grow a beard; you age (gracefully or otherwise); your health and fitness changes as well, usually going steadily downhill. Changes are also apparent in your very essence which alters over time too in terms of memories and knowledge acquired and forgotten; likes and dislikes ditto. So that you at your death could be just a pale reflection of that you in your prime. But your prime isn't the maximal prime when it comes to all of the facets that make you, the you reading this right now, you. Your health or fitness could be better or worse tomorrow. Your interests different tomorrow. Your new experiences now added on to what came before; or maybe forgotten. However, you could argue that God could resurrect you in such a fashion as to combine all of the various maximal primes you had at various ages into a new and improved version of you. But what about the baby / infant who hasn't achieved any real prime bits yet. All their prime bits are theoretical and just potential future ones. But when the baby dies they had no knowledge, no real experiences, no memories, and no real fitness (physical or mental). What kind of eternal afterlife could that infant have, or does an all-knowing God just resurrect the baby knowing what kind of maximal primes it would have had? Does that really even make any sense? That sort of negates any free will that baby would have had!
The moral of this little segment is to make the fullest use of this go-round that you can for once it's done, it's done. That's it. As Yogi Berra once observed, "it ain't over till it's over", but once it's over, it's over! So "do not go gently into that good night. Rage, rage against the dying of the light."