We live in an age of excitability, agitation and venting, thanks in large part to our unprecedented leisure time and astounding technology. Yet we also want happiness, serenity and meaning, which is why so many of us keep heading for the self-help section at the bookstore. One powerful way to reach those goals comes from the unlikely revival of the Greco-Roman philosophy of Stoicism—seemingly the farthest thing imaginable from our own anxious times.

You may associate Stoicism with suppressing emotion and enduring suffering with a stiff upper lip, a la Star Trek’s Mr. Spock. Not so: Stoicism is practical and humane, and it has plenty to teach us. The philosophy may have been developed around 300 B.C. by Zeno of Cyprus, but it is increasingly relevant today, as evidenced by the popularity of events such as Stoicon, an international conference set to hold its fourth annual gathering in Toronto this October.

The Stoics had centuries to think deeply about how to live, and they developed a potent set of exercises to help us navigate our existence, appreciating the good while handling the bad. These techniques have stood the test of time over two millennia. Here are five of my favorites.

Learn to separate what is and isn’t in your power. This lets you approach everything with equanimity and tranquility of mind. As the second-century slave-turned-teacher Epictetus put it in his manual of ethical advice: “Some things are within our power, while others are not. Within our power are opinion, motivation, desire, aversion and, in a word, whatever is of our own doing; not within our power are our body, our property, reputation, office and, in a word, whatever is not of our own doing.” Understand and internalize the difference, and you will be happier with your efforts, regardless of the outcome.

Contemplate the broader picture. Looking from time to time at what the Stoics called “the view from above” will help you to put things in perspective and sometimes even let you laugh away troubles that are not worth worrying about. The Roman Emperor Marcus Aurelius made a note of this in his famous personal diary, “The Meditations”: “Altogether the interval is small between birth and death; and consider with how much trouble, and in company with what sort of people and in what a feeble body, this interval is laboriously passed.”

Think in advance about challenges you may face during the day. A prepared mind may make all the difference between success and disaster. Epictetus again: “If you’re going out to take a bath, set before your mind the things that happen at the baths, that people splash you, that people knock up against you, that people steal from you. Say to yourself at the outset, ‘I want to take a bath and ensure at the same time that I maintain my harmony.’ ” I don’t go to thermal baths much, but I remind myself of this principle every time some jerk’s cellphone rings in the middle of a movie.

Be mindful of the here and now. The past is no longer under your control: Let it go. The future will come eventually, but the best way to prepare for it is to act where and when you are most effective—right here, right now. Seneca, the Roman senator, wrote, “Two elements must therefore be rooted out once and for all—the fear of future suffering and the recollection of past suffering; since the latter no longer concerns me, and the former concerns me not yet.”

Before going to bed, write in a personal philosophical diary. This exercise will help you to learn from your experiences—and forgive yourself for your mistakes. Epictetus advised doing it this way: “Admit not sleep into your tender eyelids until you have reckoned up each deed of the day—how have I erred, what done or left undone? So start, and so review your acts, and then for vile deeds chide yourself, for good [ones] be glad.”

Stoicism was meant to be a practical philosophy. It isn’t about suppressing emotions or stalking through life with a stiff upper lip. It is about adjusting your responses to what happens, enduring what must be endured and enjoying what can be enjoyed.

—Dr. Pigliucci is the K.D. Irani Professor of Philosophy at the City College of New York. This piece is adapted from his new book, “How to Be a Stoic: Using Ancient Philosophy to Live a Modern Life,” published by Basic Books.