I was in luck, because my friend, who lived in the same area, had his private car and gave me a lift every day.

was 是 be 动词的过去式，表示过去的状态或情况。 in 是介词，表示"处于某种状态或情况中"。 luck 是名词，意思是"运气、好运"。 was in luck 是一个固定短语，字面意思是"处于好运中"，即"很走运、很幸运"的意思。