This has become more real to me lately. I've intellectually known that everyone has an eternal soul that will be spent somewhere because that is what the Bible teaches, but I had cognitive dissonance and thought of the unsaved as just ceasing to exist when they died. When you think of people just ceasing to exist, it doesn't seem as critical that they get saved. When you know that they will spend an eternity in torment in Hell, it really urges you to witness and not take the easy route.
I don't think I will ever fully come to terms with Hell. But it is in the Bible so we need to believe it. I just try my best to trust God that His plan is better than mine.
Hell is actually mentioned more than heaven in the Bible.