I read a fair number of books that focus on themes around the maxim "know (and improve) thyself." What still surprises me is that despite the fact that many of them don't take immortality or their purpose in life for granted (as I do), they don't feel prevented from insisting on some common elements of a well-lived life. I think we would do well, as Catholics, to be more mindful of a few of these elements.
Put away your cell phone. Stop checking your watch. Enjoy this moment, whether you are alone or with someone. Whether you are at work or play or prayer. These precious moments have been given to you to prepare for eternity. Use them well, and rediscover the joy of devoting all your attention to one thing at a time.
Have a Routine
I've heard this from the pulpit often, and it's backed up in the lives of those, both past and present, who have been successful in this world. A routine allows you to automate your life and consequently focus in order to make better and more thoughtful decisions. It allows you to know the general outline of your schedule by heart, and it gives your body a predictable cycle to heal and repair itself.
Accept Mortality and Act Accordingly
Nearly all of the self-development authors I read are quite mature about the reality of death. They, surprisingly, don't encourage hedonism as an answer to the death sentence we laid upon ourselves in Eden. They encourage a conscious striving to be the best person one can be, in accord with one's values. How much easier is this path for Catholics - who have our values implanted in us by the natural law, then nourished by the rich and tilled soil of the Church and her direction and gentle law, and perfectly exemplified in the lives of the Saints?
How often does Our Lord look at "outsiders" in Scripture, whether it's a Samaritan leper who returned to show gratitude, or a Roman who insisted that he was not worthy to host Our Lord in his house? We are aware that Our Lord often uses these outsiders - these worldlings - to catch us up in His grace. In so doing He also gives us hope that those worldlings will find Him, as He is at the end of all sincere searches for Truth. Let us not let these worldlings, who do not necessarily know Our Lord, outshine us in a proper use of the gift of this little life.