Obedience is important.  It demonstrates the value you place on your commander as well as on the command.  Paul, as an Apostle, had the right to command obedience to the gospel.  Christians are not only to respond with joy at the knowledge of sins forgiven; but if they value Jesus and all that He has done, they should reject disobedience and put everything into pleasing Him (Titus 2:12).  The Philippian church had started well, while Paul was with them, and he has now heard good reports of their faithfulness to Christ: but they need to keep going, whatever the cost (2 Timothy 3:14).

So Paul reminds them that they don't just follow Jesus out of habit or because they think it is a good idea; they are empowered by God Himself.  It was the Holy Spirit who convicted them of sin (John 16:8), and helped them trust in Jesus, and He had continued to motivate their desires and strengthen their wills.  Indeed, without this Divine help, none of us could sustain living as a believer.  

But we have to cooperate.  We have to choose to shun all that God hates, and delight to do whatever God loves.  It is hard work as we wrestle with our sinful nature as the Lord gives us the strength.  But if we do not want His help we will not change.  Both God's enabling and our out-working is necessary for spiritual growth.  It is similar to an athlete's coach who gives motivation and encourages discipline so that the technical training can produce medals: but the athlete has to cooperate and commit him/her self to following the coach's instructions, with every thought in their mind and muscle in their body (Colossians 1:29).

So it is with us. However great your joy at starting the Christian race, you have to get to the finishing line.  The same Jesus, who started you running, will meet you at the end (Hebrews 12:1). He wants to be able to greet a winner who has overcome in His Name.  So, start this day by remembering that He who calls you is faithful and He has the power to see you through (1 Thessalonians 5:24).  But also remember that you personally have to walk through each day and work through each challenge to His praise and glory.  Perhaps a friend or colleague might be encouraged by this reminder that we cannot live the Christian life alone, but neither can we be passive.  Charles Spurgeon, the 19th Century English preacher said, "The Christian should work as if all depended on him, and pray as if it all depended on God" (1 Corinthians 15:10).