This scripture talks about working out salvation with fear and trembling. But it is often asked, if we are saved why do we have to continue to work it out?
I think one of the best ways to describe being a disciple is comparing it to a journey. If you were to go on a long journey, you would have to do substantial planning so that you would be safe, secure and knowledgeable about where you were going. Traveling with someone else also makes the journey easier and less burdensome because you can look out for one another( like teamwork) and share the planning responsibilities. If for some reason you get to a point on the journey where you are not sure where which direction to go, you have another person to talk through the decisions that need to be made. Those extra sets of eyes help you along your journey. You would never start a long journey with just one or two days worth of food or funds either. If you knew it was a long journey you would do whatever it takes to be prepared and also have as much help as you could get.
So now back to Discipleship, its really a lifelong journey that you start when your a baptized. The body of Christ is our support center, our help as we travel down the road of our own journey to God. Working it out, is getting help. Its also learning how to change and adapting our behavior to make character changes. character changes are hard, they can bring on a lot of fear and even some grief as we try to develop into a people that want to be like Jesus. This makes the need to have people in your life, your journey, even more imperative. Persisting or perseverance is just as much about keeping people around you as it is for growth in your knowledge of the Bible. Its a culmination of these which helps you to keep going.