Hebrews 12 1-2 Commentary?

Hebrews 12 1-2 says:

Therefore, since we have so great a cloud of witnesses surrounding us, let us also lay aside every encumbrance and the sin which so easily entangles us, and let us run with endurance the race that is set before us

What does it mean? Commentary?

Our writer begins by giving us this picture of a cloud of witnesses. The idea here is a massive host or group. And the group he has in mind is the saints he spoke of in chapter 11 along with all the rest of God's people who have ever believed before Christ came into this world, but who had placed their faith in the Messiah to come.

The main theme of Hebrews may be stated thus: The knowledge and assurance of how great this High Priest Jesus is should lift the drifting believer from spiritual lethargy to vital Christian maturity. Stated another way: The antidote for backsliding is a growing personal knowledge of Jesus