I reason out my thoughts on possible life after death this way: There either is something afterward, or there isn't. If there is life after death then we'll discover it when we get there. If there is no life after death then, of course, it will be nothing more than "lights out" when we die.
If there is nothing after this life then I think we should not waste our precious time thinking about something that does not exist. Life on Earth is short, no matter how long we live.
If there is life after death, we'll discover it when we get there; and I believe, then, that there must be some purpose to our being on Earth. If there is a purpose then I think we are expected to devote our thinking, time, and energies to that purpose. If there's a purpose, it would mean that there is that proverbial "time for every season", and the "season" while we're on Earth would be to deal with life here. When this "season" ends we can move on to the next stage.
To me, either way, life on Earth is short. Nobody can ever know for certain if there life afterward, so it makes sense to wait until we see if/when we get there; and deal with it then. If there is nothing then imagine all the wasted time people have spend thinking about it, planning for it, and even dying for it.
I tend to think that it is unlikely we can bring our thoughts and personalities with us, once the brains that support them are dead. In other words, I tend to think that once we're dead it's "lights out". I reason, though, that if there is something/someone else after this life, my choice to focus on the gift of a brief time on Earth while I'm here would be seen as appreciating that gift and doing my best to honor it.