Over the last decade or so, the term Memento Mori has become rather well known. It's a call for men to wake up, get off their arses and seize the day. It translates as "Remember you are mortal" or "Remember that one day you will die". While this perspective is certainly needed, it's only 1/2 of the equation, and, I believe that it is actually making it harder for many men to make decisions that move them forward.
In contrast to Memento Mori, Memento Aeternum calls us to "Remember that we are Eternal". Why is this significant? When we have too much focus on this life being our only shot, we can get locked in indecision. Every decision has consequences, and most decisions mean selecting one potentially good thing and leaving 5 other good things on the table, never to be tried.
As we get older, the pressure begins to mount. A career decision at 25 can be reversed in 10 years without missing a beat. A career decision at 45 is a different story.
If we become too focused on our time in this life, we can get decision anxiety because so much is riding on us making the right choice: who we marry, where we live, where our kids go to school, etc. What ends up happening is that we stop taking risks, or, swing the other way and try to experience as much as we can.
However, when we remember that we are eternal beings -- and if we can truly believe that -- then we can live with a kind of freedom that is not devoid of rationality. We can live with an expectation of a future greater than we can imagine. Of course, I believe this only truly applies to the Christian. Everyone else is suspect to disappointment in this matter.