In him we have obtained an inheritance, having been predestined according to the purpose of him who works all things according to the counsel of his will, (ESV)
There are two key words here in this verse that I want to look at today: "work," and "will." Paul is talking about God's working and his will. And I want you to think of that in stark contrast to our work and our will.
We may have the will to do something, but as we all know, the work does not always follow our will. The flesh may be willing, but the rest of us is week! Every time I look at the mess accumulating in the inside of my truck I declare, "I'm going to clean up this mess!" Now, it has gotten to the point that if a homeless man was living inside the mess I would be unable to find them.
All silliness aside, I want you to consider the idea of our eternal salvation and right standing with God. Even if a person would "will" to have a relationship with God, they would be completely incapable in their works to achieve it. Man's will and work are not the same as God's. In the letter to the Romans, Paul describes this inability of Man's will:
 For I know that nothing good dwells in me, that is, in my flesh. For I have the desire to do what is right, but not the ability to carry it out. (ESV)
I am thankful that the story of our lives does not end with the despair of our will's inability to work. Rather, there is a God who has a divine will that works perfectly. He "works all things according to the counsel of his will." It gives me great comfort to know that I am not responsible for the great work of providing my salvation, were I even able to will it. God willed that those he predestined would be saved. And he worked that salvation according to the counsel of his will. Salvation is initiated by God, and completed by God.
The writer of Hebrews describes God's amazing work on our behalf. And he also encourages us to run with endurance the race that we are in as Christians. What is our motivation? The faithful ones who have gone before, and the Savior himself who founds our faith and perfects it. Hear these beautiful words:
 Therefore, since we are surrounded by so great a cloud of witnesses, let us also lay aside every weight, and sin which clings so closely, and let us run with endurance the race that is set before us,  looking to Jesus, the founder and perfecter of our faith, who for the joy that was set before him endured the cross, despising the shame, and is seated at the right hand of the throne of God. (ESV)
Are you feeling weak in your battle against sin? Are you doubting if you will make it? Be encouraged! God is the author of your faith. His work and his will is perfect, even as your work and will is weak and incomplete. Trust in Him. Rely on His strength. He finishes what he starts, and that includes the work that he has begun in you.