What is the true purpose of our lives?

I recently penned a piece about what it means to "grow up." It never really got to a fundamental question of life, one that starts early on and likely never loses its relevance. It was so long ago that I don't even remember the first time someone asked, "What do you want to be when you grow up?" It was likely my mom or some elementary school teacher. I didn't know then and I likely still don't know today the real answer to that.What do you say when the response (to the degree that it is answerable at all) is not definitive, rather it is part of a process? The "what" I wanted to become and what I "became" have changed and morphed over time.I was once a soldier. I graduated from West Point and chose an assignment with a forward-deployed combat unit on the edge of the Iron Curtain. I "knew" that this was the career for me. I wanted nothing more than to command troops in combat. For a host of reasons, some personal, some professional, things didn't turn out that way.I became an academic (actually more a soldier-scholar). I taught strategy and security policy at a time when the theory of how you contain communism and deter war was as important as the execution on the front line (where I previously stood watch). That world collapsed and the fulfillment of teaching faded.I left the Army with the conviction that I did not want to do anything I was qualified for (consulting or teaching defense policy). It would be a fallback, but I knew that I would never move forward once I entered that realm. After working for a huge bureaucratic organization, I wanted to be the master of my own fate. I got that opportunity with another West Point grad. He brought me to this region. It was the land of opportunity for me. Eventually, I started my own business. I have had multiple companies and failed many times along the way (the typical trajectory for an entrepreneur), but ultimately built productive ventures. The circumstances that set the stage for that particular success have waned, and I have largely exited that field of endeavor.So here I sit, in my mid-60s facing the same question asked of me some 50 years ago (and innumerable times since then), "What do you want to be when you grow up?" Today, the major difference is that I don't have to "do" much of anything. I could retire and be relatively comfortable sitting in the sun sipping drinks with fruit garnish and little umbrellas. That seems a quick path to insignificance and ultimate expiration.Of course, we all reach our "expiration date." The conundrum (at every stage of our lives) is what to do until then. The question is relevant no matter where we are along life's path and no matter how brief or lengthy that journey may be. Mark Twain put it concisely, "The most important days in your life are the day you are born and the day you find out why."The accomplishments of this temporal world are the least significant factors, no matter how great or lesser they may appear. The important question is whether we have lived our lives in concert with (what my former pastor, Greg DePriest rather eloquently put) "all that God designed us to be." Or as my father said it, "Have you put to the best use the gifts God gave you?" The fact that the same notion can be stated by so many different people in different words seems to attest to its universality.So here I sit (quite literally at the moment) well into the second half of my life, faced once again with that epic question. I grapple with the answer just as much today as I did in my youth. It is what drives us (or ought to drive us) in our thoughts and actions.Despite my age (or perhaps because of the knowledge I have accumulated over those years), I have a firm conviction that all the lessons I learned and the "tuition" (cost) I paid to get it have brought me to this place. Or perhaps I should say that God has led me to this place.I see the road ahead. I also understand that more tuition must be paid. Those frustrations and sacrifices may be high, perhaps ultimately ones that I cannot or am unwilling to pay. Moreover, I am concerned that my conviction that I am "doing what God wants me to do" may turn me into a zealot rather than a facilitator of His will.If I am honest with myself (a struggle for me), I don't really know if this is the right path, or whether this is even what I want to do. However, I do believe it is what I was designed to do — but can we ever really divine the true purpose of our lives? All we can do is try.