The weight of a 20 lb. sandbag is great for physical training, but what about running our spiritual races with the burden of sin on our shoulders? Not nearly as productive or helpful!
The weight you carry today might not be sand, but a mixture of regrets, anxiety, and worry. Or maybe you're struggling under the burden of unforgiveness, resentment, and fear. Or perhaps you’re carrying around lust, greed, and pride. Regardless of the specifics, our sins weigh heavily on our souls when we fail to confess and bring them to the Lord. As Christians, we have confidence that the Lord is faithful and just to forgive our sins and cleanse us. Why don't we just pass it over to Him rather than stumbling around sweating and struggling? 
This verse urges us as believers to “lay aside every weight” so that we can “run with endurance.” Repent! Put those weights down! Run with endurance, like the “cloud of witnesses” did that have gone before us. Christ's completed work on the cross destroyed all the weights we still try to carry. Let's run the race set before us with patience and endurance. When we look to Jesus, the Author and Finisher of our faith, we know we're on the right track.

Dear Heavenly Father, help me let go of anything that would hold me back from embracing everything You have in store for me in Jesus's name. Thank You for sending Jesus Christ, our Savior, and freeing me from the chains of my sins. Your sacrifice is not something I take for granted, and the only way I can repay You is to keep my eyes on You and only You. Help me run the race that You've set before me with perseverance. I know You have always been there for me and will always be. In Jesus's name I pray. Amen.