Jesus, help me to simplify my life by learning what you want me to be and becoming that person.
Attr. St. Thérèse of Lisieux
This sounds a lot more like someone’s meditation on St. Thérèse’s Little Way than it does anything that she herself might have written. A friend points out that St. Thérèse very rarely wrote out her internal prayers.
Googling in general didn’t turn up much. I did find one site claiming that it’s from Story of a Soul, but searching an online edition for simplify, learning, becoming, and person turned up nothing. Google Books doesn’t have it before 2009.
One site said they found it in a Christopher’s pamphlet, and I was able to find a Christopher’s News Note link via Google, but the link doesn’t work (404 error). I tried looking at some likely-looking titles on the News Notes page, but none of them contains the alleged quotation (and what citations I did see were secondary sources that are notoriously unreliable).
It’s not on Wikiquote at all.
I am fairly confident that St. Thérèse didn’t write this. Among other things, I’ve observed that real quotations usually turn up in the first page or two of search results, and I went double-digit pages looking for this one.
They didn't say it 