Upon her entrance to the Congregation Helen received the name Sister Mary Faustina. Her novitiate she spent in Cracow, and there, in the presence of Bishop Stanislaus Rospond, she pronounced her first religious vows, and five years later, she made her perpetual profession
of the vows of chastity, poverty and obedience. She was assigned to work in a number of the Congregation’s houses, but for a longer period in those of Cracow, Plock and Vilnius, fulfilling
the duties of cook, gardener and doorkeeper.
To all external appearances nothing betrayed her extraordinarily rich mystical life. She zealously went about her duties, she faithfully observed all the religious rules, she was recollected and kept silent, all the while being natural, cheerful, full of kindness and of unselfish love of neighbor.

The austere lifestyle and exhausting fasts that she imposed upon herself even before joining
the Congregation, weakened her organism to such an extent that already during her postulantship it became necessary to send her to Skolimow near Warsaw to restore her to health.
Towards the end of her first year of novitiate she was visited by unusually painful mystical experiences of the so-called dark night, and later by the spiritual and moral sufferings related
to the accomplishment of the mission she was receiving from Christ the Lord.

Faustina laid down her life in sacrifice for sinners and on this account she also sustained diverse sufferings, in order by means of them to the aid their souls. During the last years of her life inner sufferings of the so-called passive night of the soul and bodily diseases grew in intensity.
The spreading tuberculosis attacked her lungs and alimentary canal. For this reason twice
she underwent several months’ treatment in the hospital on Pradnik Street in Cracow.
Physically ravaged, but fully mature spiritually, she died in the opinion of sanctity, mystically united with God, on October 5, 1938, hardly 33 years old, having been a religious for 13 years. Her mortal remains were laid to rest in the common tomb in the convent’s cemetery in Lagiewniki in Cracow. In 1966, during the informative process towards Sister Faustina’s beatification, her body was transferred to the convent chapel" (text cf. with the footnotes of the Saint Faustina’s DIARY).