the warmth of the sun

Psalm 80: 3, "Restore us, O God; make Your face shine upon us, that we may be saved."

Merrian-Webster (it's a dictionary...remember those things?! 😉) defines restore
1.  give back, return
2.  to put or bring back into existence or use
3.  to bring back to or put back into a former or original state
4.  to put again in possession of something

Israel had lost its favor with God.  He was letting them experience His anger for their disobedience as shown by His silence.  He wants God to give back His favor so that they again can be used to make Him famous.  In those ancient times, most civilizations worshipped many gods (polytheistic) that explained and controlled nature.  The Hebrews were the first to worship the One God (monotheistic), the God of Abraham, Isaac and Jacob.  People were watching them.  When they struggled, their enemies mocked their God.  Asaph asked that God would bring them back to their original state as His chosen people promising their obedience, "Then we will not turn away from you; revive us and we will call on Your name. (v. 18) Israel, again, wants to possess God's favor which is pictured by God shining His face on them.

The Israelites realized their salvation came from God, the One who restores us and rescues and saves so we can have relationship with Him.  If you ever walked in disobedience and for a moment felt His favor (NOT His love) leave, it is a lonely and sad feeling.  So much so, Asaph repeats this plea each time with what feels like increasing fervor. "Restore us, O God Almighty...(v.7)", "Restore us, O Lord God Almighty...(v. 19)".  God's absence feels cold and alone, nothing like basking in the warmth of His beautiful face shining down on you.