It's cross to bear, bear in this case being used in the same sense it is in weight bearing, Greeks bearing gifts or even ball bearing. It refers back to the Biblical tale of Jesus carrying his cross to Golgotha.
Lookin' Out My Back Door. Lookin' Out My Back Door is a song recorded by the American band Creedence Clearwater Revival, also known as CCR. The song was written by the band's lead singer, guitarist, and songwriter, John Fogerty.
Robert Allen Zimmerman, better known as Bob Dylan, wrote and performed Knockin' On Heaven's Door for the soundtrack of the 1973 film Pat Garrett and Billy the Kid.