Have you ever been totally beaten down by stress? Felt too overwhelmed to function? Believed you'd broken your psychological energy?

Six years ago, I broke mine.

I was in the middle of an intense season of speaking engagements, business challenges and life at 30,000 feet--when I unexpectedly lost my brother Tim to brain cancer.

In the months following Tim's death, business demands were relentless. I took little time to grieve. But I should have--because all the stress and suppressing of my emotions ultimately damaged my resilience.

The ability to quickly "bounce back"--something I took for granted in my youth--was nowhere to be found. I would sit at my computer with a vacant stare. I felt "off" and inappropriate socially. I lost track of my purpose.

Thankfully, I'm back in the game now. It took some time, but my path back to productivity closely maps that of resilient survivors everywhere.

If you're feeling like you're at the end of your rope, here are some tips based on science to help boost your emotional immune system, reboot your resilience--and quicken your ability to bounce back to your normal self.

First, know your nature

Start your path to resilience with this empowering knowledge: You come hard-wired with an internal bounce-back imperative.

"Resilience is not a genetic trait that only a few 'superkids' possess," writes Bonnie Benard. "Rather, it is our inborn capacity for self-righting...and for transformation and change."

In fact, bouncing back is a universal instinct we all have. It comes in the form of innate self-righting tendencies, which help us meet our needs in times of adversity. In essence, this instinct helps us protect our own human growth and development.

Second, choose your nurture

Resiliency research identifies three elements--or "nurtures"--that boost our ability to get back in the game: relationships, belief, and contribution.

1. Relationships
Extensive research shows the best predictor of your physical health is not the quality of your diet, how much you exercise or whether you smoke: it's the quality of your social connections.

Why is this so? When you connect with others, a nourishing hormone called oxytocin (a.k.a. "cuddle drug") is released in your system--creating a sense of bonding and trust, motivating you to tell others how you feel, and prompting you to seek support.

But there's more. As health psychologist Kelly McGonigal says in this TED Talk, "Oxytocin acts as a natural anti-inflammatory, relaxing your blood vessels, protecting your cardiovascular system, and regenerating your heart cells."

Resilient people nurture themselves by creating micro-moments of connection.

How to practice resilience: Turn a transaction into a conversation. Offer or ask for a hug. Eat lunch with someone, rather than alone. Or tell someone what you really need, rather than burying it.

2. Belief
New York Times Bestseller author Tom Connellan writes that two-thirds of all entrepreneurs, 55 percent of all Supreme Court Justices, and 21 of the first 23 astronauts all have one thing in common: they're first-borns.

What makes this group of people so successful? According to Connellan, a key reason is that we expect more of first-borns--and our positive beliefs prompt us to give them more responsibilities and feedback. This fosters the perfect environment for health and growth.

There's also good news for those of us who are second/third/fourth-borns: we experience success when we surround ourselves with the first-born ecosystem: positive belief, opportunities to exercise responsibility, and a rich flow of feedback.

When we are believed in, we tend to believe in ourselves. This is vital because science shows that your brain will not allot you the resources to do something until you believe you can do it. Like a Shark Tank judge, your brain demands a sure bet and doles out resources only when it senses a high degree of confidence.

Resilient people nurture themselves by surrounding themselves with people who believe in and expect the best of them.

How to practice resilience: Book time with a person who has high expectations of you. Ask them two questions: "What do you believe is possible for me in my current situation?" and "If you were to challenge me to do one thing, what would it be?" Possibility and challenge release dopamine, a brain-nourishing hormone vital in the restoration of one's resilience.

3. Contribution
Humans are driven by a sense of meaning.

Victor Frankl, author of Man's Search for Meaning, discovered that he (or she) who has a strong why can bear any how. He observed that the people who were able to survive the atrocities of the prison camp he was in during World War II were the ones who had a piece of work they had to finish, or a relationship they had to get back to.

His conclusion: Man's search is not one for happiness, but a search for meaning.

Resilient people plug into something bigger than themselves--and find themselves fuelled by the intrinsic motivation of the cause.

How to practice resilience: What is one concrete act of service you are uniquely equipped to offer to your community? What is the very next logical step you need to take to involve yourself in that act of service? Take that step to create meaning in your life.