abstemious - adjective

When [Marcus Aurelius Antoninus (121–180)] was eleven years old, he assumed the dress of philosophers, something plain and coarse, became a hard student, and lived a most laborious, abstemious life, even so far as to injure his health. Finally, he abandoned poetry and rhetoric for philosophy, and he attached himself to the sect of the Stoics. But he did not neglect the study of law, which was a useful preparation for the high place which he was designed to fill. His teacher was L. Volusianus Maecianus, a distinguished jurist. We must suppose that he learned the Roman discipline of arms, which was a necessary part of the education of a man who afterwards led his troops to battle against a warlike race.

—George Long M. Aurelius Antoninus