I needed this prayer yesterday. I checked the source today.
The frequent ascription to Mother Teresa stems from the misreading of a book about the famous Catholic charity worker called “A Simple Path” that was compiled by Lucinda Vardey and released in 1995. The page preceding the appendices was titled “ANYWAY”, and it presented versions of eight of the ten statements under investigation. Statements 06 and 07 were omitted. A note at the bottom of the page said [MTLV]:
From a sign on the wall of Shishu Bhavan, the children’s home in Calcutta.
So the words were not directly attributed to Mother Teresa. Instead, some person at a children’s home operated by her charity organization posted a note with the sayings. Nevertheless, one or more readers of the book decided incorrectly to credit Mother Teresa with the sayings. —Quote Investigator