Mind Over Muscle: True Strength — Letters from a Stoic

The old Roman greeting was 'If you are well, it is well.' Seneca suggests a better version: 'If you are studying philosophy, it is well.' Without it, the mind is sick, and a sick mind makes even the strongest body no more than a madman's strength. Letter 15 takes aim at the Roman obsession with physical training. No amount of muscle work makes you stronger than a bull, he points out, and stuffing the body to build mass only dulls the mind that rides inside it. He isn't against exercise, he recommends running, jumping, short bursts of effort that tire the body quickly and leave the rest of the day for thought.

The body needs brief labour. The mind can be exercised day and night, in any weather, at any age. One improves with time. The other deteriorates if you pour everything into it.

The letter closes with a Greek proverb Seneca calls excellent: 'The fool's life is empty of gratitude and full of fears; its course lies wholly toward the future.' The trap isn't wanting too much, it's never noticing how much you've already gotten. Seneca's challenge to Lucilius is simple: when you see the people ahead of you, turn around and count the ones behind. Better still, measure yourself only against who you were.

Fix a limit you wouldn't want to pass even if you could. That is where the restlessness ends.