Isaiah 40:1-2
He is speaking to the kingdoms of Judah and Israel. Their warfare was hard service.
Isaiah 40:10
The Lord had already secured His exaltation. He has been rewarded. Also, I think His reward could be those that come with Him in the first resurrection. They act as his arm, and rule for them.
Isaiah 40:16
With the Lord's glory, and majesty, the earth is so small along all His works. Even burning all the cedars in Lebanon would not begin to be a worthy sacrifice unto Him.
Isaiah 40:26
Temple imagery:
Isaiah 40:28
The Lord never gives up on us. :)
Isaiah 40:30
Even the young ones, with so much energy and enthusiasm do not have the strength to stand against all.