Aflight en route to Tucson, a couple seated next to me explains they are headed to the desert to celebrate their 40th wedding anniversary.

“Forty years,” I say, “that’s remarkable. What’s your secret?”

Both husband and wife cock their heads, then exchange looks; it appears they have never considered this subject. They study the other to determine who should speak first, when finally the husband turns to me.

“I think,” he says, “that whenever one of us wanted to give up, the other one wanted to keep going.”

Celebrating an anniversary amid the spiky aridity of the desert seems a contrast to the lush abundance four decades of marriage suggest. Then again, maybe it is the perfect setting: Consider the saguaro impossibly flowering against a hallucinatory plane of nothing but quicksilver mirages or the vermilion flycatcher submitting to a sere, sedimentary wind to carry it home. This is a scape of nature where any frame presents perseverance and surrender in perfect balance. But, for human nature, when to do which can be as elusive as desert water.

After all, as much as we may exhort the resolve of the athlete who will never succumb, perseverance becomes masochism when we speak of an abused spouse. As much as we laud the anchorite who abandons the material world for the immaterial, surrender becomes sadism if we are told of someone who abandons his lover after she receives a terminal diagnosis.

Understanding whether to stay the course or give up — as individuals, couples, even societies — begins by understanding what makes each positive and negative. Healthy perseverance, and healthy surrender, are first and foremost tied to healthy motive, says Prudence Gourguechon, a Chicago-based psychoanalyst and psychiatrist:

“All of us persevere at least some of the time based on our values…. If you’re an ‘uncoverer’ of secrets, for example, that can determine an occupation that involves looking deeper and deeper for an explanation: a journalist, a detective, a scientist. Another motive is talent—like the athlete.”

But, says Gourguechon, “there are negative motives to perseverance, such as group pressures. There’s a lot of social science on group-think and how it is really hard to buck.” The financial crisis is a good example of people continuing to do dumb things because everyone else was, she argues.

As for unhealthy surrender, Gourguechon points to what colleagues have called the “bully-bystander” phenomenon:

“When the bystander does nothing — certainly a form of surrender because they don’t want to get involved — that’s destructive. Or any time we turn a blind eye with things like climate change or human trafficking.”

Perseverance can also become problematic when it’s based on fear. “Holding on to people, places, things, and ideas that no longer serve us; this is when commitment shifts to compulsion,” argues Dorothy Adamson Holley, a developmental psychologist and clinical social worker in Baltimore. At moments like these, surrender becomes a healthy motive—perseverance’s necessary antidote.

Perseverance and surrender may not be polarities at all, however. “The Buddhist perspective on perseverance and surrender is that both are called for,” says psychologist Dana Jack, author of Silencing the Self Across Cultures: Depression and Gender in the Social World. “They’re part of the six paramitas, or six perfections, having to do with what might called ‘joyful endeavor.’” Motive is everything, Jack concurs, and the healthy versions of perseverance and surrender “must be aligned with our heart and values, or some deeper inner prompting.”

“If someone is blindly following a role or a teaching, then they’re surrendering to something outside them that is telling them what to do.” Jack says depression is often the signal that we are following one of these virtues to the detriment of the other and ourselves:

“If you surrender to the idea of what a good wife is, that’s not perseverance because you’re not pulled by genuine love for this person, but by an image of what it is to love.”

She’s noticed something interesting:

“When people in marriage counseling are at the end of things, they [often] say to the partner, ‘Okay, the relationship is over, so this is how I really feel,’ which is when things often get better.”

In other words, surrender can often be the gateway into a frank confrontation with the self and others, and lead back to a renewed commitment to persevere. Artists often speak of this phenomenon, noticing that in letting go of a creative problem, the answer emerges.

Before we can identify whether our motives are healthy, however, there’s work to do. Some of it involves actually persevering or surrendering to arrive at our answer. First, we must surrender to the notion that this won’t come easily.

Lou Manza is among a burgeoning cadre of researchers who study “grit,” an earthier term for perseverance. His research focuses on college students and stems, he says, from seeing more and more kids in the classroom who are pushing less and less. When things get difficult, Manza claims, they back off. In Manza’s view, however, the life choices that involve deciding when we should persevere or surrender are usually of such complexity and magnitude that grit becomes essential to those decisions — in particular, what he calls our “grittiness to know.” Manza believes we cultivate that gritty curiosity by recasting self-reflection as a pleasure born of hard work, not a burden — again applying the Buddhist principle of “joyful endeavor.”

“You have to engage in the difficult things,” says Manza, who chairs the psychology department at Lebanon Valley College in Pennsylvania.

“To really be good at something, you have to [start by] knowing it won’t come easy. Take technology. Rather than people going outside and sledding in the winter, for example, they’ll play a videogame where they’re sledding on the screen. They’re missing something. They’re not going down hill, learning the skills, learning how to cope when the sled turns over, learning about fear and getting back up. That develops a bigger life skill that carries over. Not doing the hard work of things means not reaping the real rewards of them.”

What Manza encourages is a reconnection with firsthand experience and a psychological shift that defines the experience of hardship as necessary for progress:

“Many religions would say that one of the most difficult obstacles on the spiritual path is laziness.”

A key way to develop a discipline of self-reflection that will demystify the choice to persevere or surrender is to play out the scenarios we are attempting to decide upon and argue the opposite view as effectively as we would argue our own. This is especially helpful in relationships, Gourguechon says.

“What happens if I stay? What happens if I go? Have I tried to identify what’s fixable and tried to fix it? Have I tried to identify what my contributions to the situation are and what’s fixable in myself? Have I made a conscious effort to remember and remind myself of the good points of the other person, what he or she brings to my life in big and small ways? If you can’t think of anything, that’s a clue.”

But most people don’t take the time to step outside themselves and rigorously consider the point of view of the other person.

This sort of hard psychological work can benefit conundrums beyond the heart. The geopolitical, for example: Is persevering in our devotion to political party always the wisest choice? Or, consider war. When does perseverance stop being heroic and become maniacal?

“Rigidity,” adds Gourguechon, “is sort of the enemy of everything.”

Like the Tucson couple who cycled in when the other was cycling out, knowing what to do when may ultimately require people to be much more tolerant of ambiguous and negative emotions than we generally tend to be now. To stop turning away from what’s negative or ambiguous can be useful in all areas of life, from politics and work, to marriage and parenthood. In fact, our culture’s current penchant for positivity can make us allergic to anything that even hints at the negative, some psychologists argue, and in turn prevent us from knowing how and when to forge ahead or retreat.

“I would be remiss as a psychoanalyst if I didn’t bring up anxiety here,” says Gourguechon. “I think it plays a huge role in the choices people make for surrender or perseverance. Biologically, anxiety is a warning that there is danger to prepare for, but I think a person can become crippled by anxiety. Lots of times anxiety makes us stop doing things we shouldn’t stop doing, and makes us persevere when we shouldn’t. But it’s okay to experience anxiety, or guilt, or uncertainty. It’s more than okay. Being able to tolerate negative emotions is a sign of emotional maturity.”

Those who are steeped in nostalgia often exhort how much stiffer our upper lips were in the past, possibly because past eras had less expected comfort. But Jack, herself a veteran of a 47-year marriage, says that philosophy has its own sufferings:

“It depends on what we want out of relationships. Today, the general person might want everything out of their relationship — intimacy, really good sex, everything. The generations before us didn’t have the same demands. Their expectations were fewer. So they were willing to surrender, to be more accepting, and to persevere…[but] their perseverance might have been more like self-subjugation and resignation to unhappiness than weathering the ups and downs of a rewarding relationship.”

But there’s something we can borrow from past generations that will help sharpen our ability to judge whether to persevere or surrender. We need to focus more on serving others, Gourguechon says.

When we are exposed to the struggles of others, we develop an aptitude for tackling our own dilemmas. Engaged but one step removed, the complexity becomes less scary, emotions less thorny, the final destinations indicated by the choice of perseverance or surrender less fraught. The more we act as a presence in other lives, the more present we become in our own. The more we participate in the labyrinth of another’s dilemma, the more adept we become at delivering ourselves out of our own — via persistence or surrender.

When the Tucson couple debarks from the plane, I wish them good luck, though something tells me I don’t need to. If we long for as long a love as this couple has had, it is ultimately because we wish to engage in that stark dance — or duel — between perseverance and surrender. The good news is that love may be our best lab for coming to see these virtues less as polarities, more as a pair. It is love, after all, that itself offers us an ecstatic paradox: a desire that begins and persists in the self, but aspires to leave that self behind.

This post was originally published in The Washington Post on June 2, 2015.