We must also make ourselves flexible, to avoid becoming too devoted to the plans we have formed, and we should make the transition to the state that chance has brought us to without dreading a change either in our purpose or our condition, provided that we are not falling prey to fickleness, a vice entirely at odds with repose. For stubbornness, from which Fortune often forces some concession, must involve anxiety and wretchedness, and at the same time fickleness is much harder to bear when it fails to control itself in any situation. Both are hostile to tranquility, both the inability to undergo any change and the ability to show endurance. Above all it is necessary for the mind to be withdrawn into itself, abjuring all external interests; let it have confidence in itself and take pleasure in itself, let it admire its own possessions, withdraw as far as possible from those of others, let it not feel losses and put a kind interpretation even kn adversities.

Seneca, ‘On the Tranquility of the Mind’