Every time I ponder about the whole concept of eternity it boggles my mind. Webster's defines it as "infinite time" or "endless or immeasurable time". I always think of it in terms of God, who is, who was, and who is to come. I can't wrap my brain around how He had no beginning and He has no end.
Add to that all of His creation and our puny understanding of the concept of the universe. If we could take off in a rocket and travel to the end of "space"... what is beyond the end? Mind blown every time! Scientists have their theories and explanations, but only the Creator knows. We'll never truly grasp it all.
And then there's heaven... WOW! We get to spend eternity there with our LORD. That's a long time!
Genesis 1:1 (NLT) - "In the beginning God created the heavens and the earth."