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.
As a result, many of the songs on In Through The Out Door were put together by Plant and Jones, with Page and Bonham adding their parts late at night. This song is not a love song in the traditional sense, rather a tribute to Robert Plant's son Karac, who died of a stomach infection in 1977 when he was 5.