One of the primary aims of Christianity is to invite as many people who are far from God into the joy that we have in Him so they can experience it with us. To fight the good fight, finish the race and keep the faith means not only enduring in the gospel ourselves until our homecoming, but also equipping others with the gospel so they can fight on, race on, and keep on when we have gone on, until there is no place left that has not heard the good news of Jesus. A life well-lived is one in which we press on in the faith ourselves and pass on the faith to others so that God is honored in more of us and more of us are happy in Him.
