Looking unto Jesus, the author and finisher of our faith, who for the joy that was set before Him endured the cross, despising the shame, and has sat down at the right hand of the throne of God."
Hebrews 12:1-2 (NKJV)
When you take a trip somewhere, it is necessary to pack a bag with what you will need for your trip. What you pack, and how much you pack, will depend on where you are going and how long you will be there. People normally take these things into consideration when they are packing, because it would be foolish for someone to just grab some random things and put them into a suitcase without stopping to think about if what they are packing is really necessary for their trip.
Hebrews 12 talks about a race that is set before us, which is referring to the life that God has called us to live. The Bible talks about how we should live a life that fully pleases God (Colossians 1:10), and we see how Paul said that what really matters is finishing the race that God has called us to run (Acts 20:24). But we must consider not only how we are running, but what do we have with us as we run our race? Are there things we are taking along with us on our race that we really do not need?
In the same way that no one would pack something that is unnecessary for a trip they are taking, we do not want to have things in our life that are unnecessary and that could weigh us down as we run our race for God and do His will. We need to be sure that we only add things to our life that are really necessary to run the race God has called us to run. If our life is filled with things that we do not really need to fulfill the will of God, then we are just adding unnecessary weights to our life that will slow us down and hinder us from doing the will of God.