Turn to any page of St. Faustina’s Diary, and you’ll find spiritual gems. Like this one: 

My daughter, write that it pains Me very much when religious souls receive the Sacrament of Love merely out of habit, as if they did not distinguish this food. I find neither faith nor love in their hearts. I go to such souls with great reluctance. It would be better if they did not receive Me (Diary, 1288).