When I was young, in a youth group with a non-christian 'leader' I was puzzled by his cynicism about how long 'eternity' would be as the after-life.
I guess his big deal would be...what the heck would we do!
Well, I've got the first 30 billions years solved.
Let's say, over history, there would be at the end, 1 billion Christians.
Now, it takes a good 10 years to really get to know someone. To really know them, probably another 10; to fully connect, 10 on top of that: a full 30 years.
So to get to really know all the others in the New Creation, co-ruling with Christ...30 billion years.
But, what next?
Solved: the infinite God gives a taste of what infinity means. We would never come to an end of exploring, learning from, growing from knowing the infinite God who is love.
This video gives an illustration of a 'tangible', but conceptual, infinity. Just think about the endless unfolding patterns it shows. Perhaps this gives a hint of coming to know the infinite creator who Is.
[If the link fails, it is Dr Lisle on the the mathematics of Mandelbrot patterns.]