What's wrong with hair shirts?

[Bernadette]

But then again, St. therese, who brought us the little way, apparently used to flagellate herself  in hercell when no one was around, so perhaps offering up the little things wasn't enough even for her.

If she went above and beyond the penances required of her as a religious, you can be assured that it was only with the consent of her spiritual director. St. Therese was a particularly generous soul, I would think, so I doubt she thought in terms of "enough."