To this end I also labor, striving according to His working which works in me mightily."
Colossians 1:28-29 (NKJV)
Have you ever had a project that you were working on that you could not complete in just a day? Maybe you were learning a new language, or it might be that you were doing some long-term home remodeling, or maybe you were in a physical fitness routine with the goal of losing weight or just being in a better physical condition. Whatever your long-term project was, you would need to keep working on it on a regular basis and you would need to make it a priority, so that you did not lose sight of the project and fail to complete it.
In Colossians 1, Paul talked about his working to present everyone perfect in Christ Jesus, meaning he was helping people become mature believers in Christ. We can see here, and with other things that Paul wrote about spiritual development, that this was a main objective that Paul had. Helping people become mature believers was a goal that Paul had, it was something he was always working on. Paul knew this was something that was not done in one day, and we can see from his life and writings that this was a priority in his life.
The Apostle Paul did many things, but he was always working on developing spiritually mature believers. Paul traveled a lot, and he was also a tent maker, but his main goal was to help people understand their relationship with God through Jesus and to help people develop into mature believers. Paul knew that unless someone grows up spiritually that they will not be in the position to do everything that God has called them to do. Developing spiritually mature believers is something that Paul was always working on, and we should too, for ourselves and for others.