When we reflect about the whole of our lives the question we ask ourselves is whether there is a way that makes them worthwhile, something that is a ground for a life's being a good life, a way for someone (that is, for you and me) to be the person we should be, the best we can make of us and of what's being dealt to us by blind fate and the accidental circumstances of our lives. Once you've found an answer to that question (even if it's only a tentative one), there's a new project for you, one that grounds your life.
Not all kinds of project are well-suite for playing this role in your life, however. You neither know when and where your life begins nor when and how it ends, in the relevant sense of beginning and ending: it begins only when you start reflecting on the whole of your life, when you figure out what to do with that life, what sort of person you want to become; it ends when all your actions have played out and their consequences are felt and consumed in the world (part of which might well happen even after your death). But the crucial thing here is that you cannot know. No-one ever can. And that imposes a constraint on the grounding project of your life: it excludes a certain type of project, the type that has a structure stretching over time, builds up and ends in a climax, reaching a high point which serves as a focal point: projects such as winning a championship, or becoming the CEO. There is nothing wrong of course with such projects in themselves; but they aren't suitable as grounding projects for the whole of your life.
Partly that's because in a project of that sort you can fail simply by succeeding. Your life is not a movie that can end with the images of the climactic moment — there is always a period after it, and though that may be fine if all this only was a project among others (you might enjoy being the CEO even more than you enjoyed becoming it, or use your status as the champion to work on training the young or become an ambassador for the environment), it's bad for you if it was the sole, defining purpose of your life, for this would mean that now you have a meaningless life on your hands.
And if your project fails for some external cause (external, in this case, means outside your own strength and activity), then stupid circumstance has had the power to defeat the purpose of your life. Thus it is not a good idea to make a project that depends on a certain structure playing out in time a grounding project.
The grounding project, then, must not be something that's exhausted in a single climactic moment. It has to be something that results in a stable condition — something that can't be taken away from you by causes external to your control. So, if we can choose, we should choose something with which we don't run that risk: a condition. Excellence.
(And of course we can choose. Remember: the starting point was reflecting on what a good life would be for you, what sort of person you would want to be. If there is anything that you can choose yourself, this is it. Everything else may be subject to an unlimited variety of factors outside of your control. This single thing is what's in your control entirely. You decide.)
Excellence of character is the condition that you're looking for. It provides a general purpose, a ground for your life. It's got the potential to make your life a good life, and successful (for success consists in achieving this goal, and if anything is, this is in your control); it can give it a primary direction, and guide decisions in specifics; it will make it worthwhile, and one worthy of a good person.
Of course, in pointing to excellence as the condition that grounds a successful life, I am merely gesturing at something that is not yet very specific; it has to be refined partly in response to the particular situation you're in. (That is, both to the circumstances around you and the current state of your character.) Just calling it the grounding project of a good life to achieve this condition doesn't make it really clear what it would mean for you to get there. So far it's just a slogan, not yet an idea that simply can supplant some serious reflection of your own. Take care.