But with the "mindful revolution" spreading in the West and a growing amount of research funding being dedicated to the study of contemplative practices and the science of compassion and altruism, the secrets of this ancient tradition are finally being recognized globally.

Early Indic cultures developed public systems of training in mindfulness -- including the Hatha Yoga tradition and Tibetan Buddhist mind training -- to ensure that the skills of contemplation and positivity were taught to everyone, explains Loizzo.

A Harvard-trained psychiatrist and a Columbia-trained Buddhist scholar, Loizzo has spent his career merging "the scientific and the spiritual," bringing ancient teachings on contemplative practice to modern Western psychotherapy and preventive medicine.

"There's a growing understanding that we need to move back in the direction of the contemplative traditions -- the ancient wisdom that says slow down, pay attention, be kind, be at peace -- whereas our modern wisdom has said that we need to just push forward and move into the future. We're realizing that's not sustainable for us either as a civilization or for our individual minds and brains. It's wearing and tearing us down just like it's wearing and tearing the planet down."

Loizzo spent years studying with Tibetan teachers in exile in India and in the West, and is convinced that the Tibetan Buddhist tradition -- which emphasizes training in mindful awareness and compassion -- has something to teach us all about how to live better lives.

Here are four essential lessons from Tibetan Buddhism that can help in your own pursuit of happiness.

Get intimate with your own mind.

We need two main things to become happy, according to the Tibetan Buddhist tradition: mindful awareness and loving compassion. The theory goes that the combination of attention and loving-kindness -- both of which can be built through contemplative practices like meditation -- can help bring the brain into its most plastic, growth-oriented state and support the development of a greater state of consciousness, Loizzo says.

Meditation -- "the quiet, humble work it takes on a daily basis," as Loizzo puts it -- is the cornerstone of the Tibetan contemplative science. Through a meditation practice, we can begin to overcome negative thoughts and habitual emotional responese, and start to live from a more calm, centered place, he says.

“Above all, be at ease, be as natural and spacious as possible. Slip quietly out of the noose of your habitual anxious self, release all grasping, and relax into your true nature," Sogyal Rinpoche advised in The Tibetan Book of Living and Dying, a guide to meditation and Tibetan Buddhist philosophy. "Think of your ordinary emotional, thought-ridden self as a block of ice or a slab of butter left out in the sun. If you are feeling hard and cold, let this aggression melt away in the sunlight of your meditation."

The research is now there to back up the benefits of this time-worn strategy for stabilizing emotions and boosting the brain's capacity for joy. Studies have shown meditation may be effective in reducing anxiety and depression, lowering stress levels, reducing loneliness and boosting emotional well-being.

"Twenty years and a thousand stories that have given me an unshakable confidence in the truly boundless potential we human beings have to heal ourselves and transform our lives," Loizzo wrote in his 2012 book, Sustainable Happiness.

Practice compassion, at every moment.

Most Eastern spiritual traditions involve some form of practice around compassion, or "loving-kindness." In Buddhism, there is a meditation for loving-kindness,“metta bhavana”, which involves sending kindness to yourself, loved ones, community members, people you may dislike, and eventually, all beings. In the Tibetan tradition, monks practice tonglen, which consists of breathing in suffering and breathing out happiness, so as to reduce pain and spread peace among all beings.

"What's unusual about the Tibetans is that they have what I call an industrial-strength version of this discipline," Loizzo says of loving-kindness practice. "These practices allow us to turn our sense of life as a battle, a struggle for survival against everybody else, into a communal experience of connecting with friends and the larger world. That, we've learned, is so important to our quality of life and our personal sense of meaning in life."

The Tibetans have devised powerful ways of helping people learn how to become more compassionate that are now being used in the Western world. A 2012 Emory University study suggested that compassion training derived from ancient Tibetan practices may boost empathy, and other studies have shown that loving-kindness meditation could increase positive emotions and lead to more positive relationships over time.

Connect with others who support your journey.

The traditional "Three Jewels" of Buddhism consist of the Buddha (the example), the Dharma (the path) and the Sangha (the community). In this tradition, the community is just as important an element as any other in living a happy, purposeful life. Increasing your happiness and well-being is a difficult thing to do alone. It requires the support and love of others, and a sense of belonging to a community.

"Modern neuroscience is showing us that we're really wired to be extremely social creatures," Loizzo says. "We're happier and healthier when we do that in a committed way ... We need to learn to connect with others with mindful openness and positivity, and to deal with the daily slings and arrows and work through those and maintain a sense of connection that's positive. This is something we practice in spiritual communities."

Strong social support networks have also been linked to a number of health benefits, including lower stress levels and increased longevity.

Embrace death -- don't fear it.

In Western cultures, our attitude toward death is largely characterized by fear and denial -- and this can, consciously or unconsciously, cause a great deal of suffering throughout our lives. But a central aspect of the Tibetan Buddhist philosophy is the belief that death should be embraced, and the concept that dying can be the "crowing achievement" of a life well lived. Although this attitude stems in part from a strong belief in reincarnation, you don't have to believe in an afterlife in order to better accept the impermanence of life in the here and now. The Tibetans believe that meditation can help us to come to terms with the nature of life and death.

When Loizzo is working with patients who are suffering from chronic or terminal illnesses, in addition to practicing meditation and loving-kindness, he goes through a traditionally Tibetan practice of asking some of life's big questions: What has been meaningful to you in your life? How do you face the impermanence of your life and the inevitability of death?

"Being able to embrace the idea of death and being present ... some of the women say it gives them a new lease on life," says Loizzo. "The ancient traditions made a science of trying to understand the death process and make meaning out of it ... This kind of approach of facing reality, even the parts that scare us, has tremendous potential for healing."

Asking these questions can help bolster an acceptance of things that can't be changed or controlled, which Buddhist teachings have long touted as a key to reducing suffering. Now, this ancient doctrine has science on its side: A recent study from Australian researchers showed that during the difficult changes of later life -- moving into residential care and losing independence -- an acceptance of what can't be changed may be a significant predictor of life satisfaction.