We need to develop a self-correcting facility that pulls us back to ourselves and our inner reason whenever we are thrown off course by external events (which are nothing to us).
When circumstances throw you off-balance, return to yourself quickly and do not stay out of kilter longer than necessary; for you will have more mastery over the harmony by continually recurring to it.
Seneca is full of hidden gems. Still in his letter on education, he outlines a number of individual character traits which, he says, owe nothing to liberal studies! Here he is on self-control:
Self-control* takes command of our desires; some it hates and routs, others it regulates and brings within healthy limits; nor does it ever approach our desires for their own sake. Self-control knows that the best measure of the appetites is not what you want to take, but what you ought to take.
*Translated as “temperance” in the Gummere passage above, but as “self-control” by Campbell.