He advocated for shunning indulgences of any kind, exercising, living simply, and avoiding vices—especially masturbation, which he referred to as self-abuse. In it, he expounded on various ways for both boys and girls to be the best they can be. \"No girl can long be beautiful without health; and no girl who enjoys perfect health can be really ugly in appearance. Girls who have these evil characteristics are very likely to have others also which are worse. And while the best age for marriage is still up for debate, it's hard to argue with Kellogg's advice for choosing a mate.