Diligence is hard. Paying attention to something over a long period of time is not often the strong suit of humanity. As time passes we get captured by the next, the latest, the easier. When someone comes along and tells us there are easier ways to be on our journey with God, we tend to be all ears. Truth over time can be distorted to fit our fancy rather than shaping our lives into what the truth demands. Paul warns Timothy about this, and encourages him to persevere in teaching pure doctrine not matter what people say about him.
The final admonishment of the chapter is to be diligent in these matters. Stick with it. I am amazed at how our commitment to the things of God ebbs and flows like the tides. Diligence is not something many of us are afflicted with and has a huge impact on our journey with God. Diligence keeps us moving in the right direction. It helps us to remain in love with God. What was true for Timothy is true for us today. We need to remain diligent in our relationship with God. The latest and greatest will come along. Someone will always have a solution which requires less. However, remain diligent to the things of God, and conform your whole life to them.