When was the last time you felt "a feeling of amazement and admiration, caused by something beautiful, remarkable, or unfamiliar"?
That's the exact definition of wonder.
But while it sounds, well, wonderful, it's also something that few adults feel or even know where to begin with re-capturing it.
Whether or not we remember it, as children, we felt it almost all the time. As babies - our eyes were wide, not because we were trying to look cute, but because our brains were bending towards the wonderful influx of new experiences, sights, colours, smells and sounds.
As adults who experience the same things day in, day out, trudge to work and have the same conversations with the same people, regaining a sense of wonder takes work. It can sometimes happen spontaneously - like when you're on holiday and get pulled into a rabbit hole of unexpected experiences - but more often than not, the predictability of life stubs it out.
To get a sense of what might be killing your sense of wonder, HuffPost UK Lifestyle spoke to experts Mark Williamson, director of Action for Happiness, 'happiness activist' Susie Pearl and co-founder of Headspace Andy Puddicombe.
When you find yourself uttering the words: "I'd love to meet up but my next free weekend is in November", you're most likely too busy. We're rushing around during the week and booking up our weekends often months in advance, leaving no room to just decompress and absorb what's going on around us.
"I think the biggest thing that kills our sense of wonder is the implicit expectation (from society and ourselves) that we need to be "doing" stuff all the time.
"Wonder happens best when we're "being" and not constantly rushing around trying to do stuff. So for a more wonder-ful life, we need to make more time for being rather than doing - even if it's just a few minutes every few hours to stop, breathe and notice what's going on around us."
Having standards and expectations are perfectly reasonable. It's when you expect things to always turn out the same way (this is a classic when having an argument with a loved one) that you utterly kill any spontaneity in a situation. Simply because something has happened a million times before doesn't mean it will always have the same outcome.
Andy adds: "In meditation we're looking to observe thought, so I always encourage people to try to cultivate an attitude of curiosity to their thinking. That's not easy, precisely because thought is commonplace, you're doing it all the time.
"So you have to try to look at this very routine, constant behaviour with fresh eyes. And I think if you can practice this in meditation, it's easier to take that sense of wonderment into other moments in your life. After all, you can sometimes feel a sense of wonder at very small things, and things that are meant to be incredible can leave you cold. So that should tell us that, once again, it's all about the mind."
Hands up how many of you have walked down the street while texting? Or spent your entire train journey glued to Candy Crush?
Technology keeps us connected in a way that we never have been before, and while there are high points, the fact is that we're missing out on so much happening around us because we're too busy glued to our screens. Wonder isn't going to come to you via your phone.
And while putting your phone down is one of the easiest ways to restore your wonder, it's also one of the hardest. Susie advises making life more simple.
"Get off technology and spend time in nature each day. Go for walks looking more attentively at colours and patterns of nature.
"Get into our senses - really notice the smells, the sounds, the designs, the textures around us. Go through each sense and really heighten awareness around each sense - even for a few minutes each day."
Similarly, answering or checking your phone when you're with a friend is a guaranteed wonder-killer. How can you concentrate on what they are saying if you're checking WhatsApp?
"Be present with yourself, a friend, a loved one. Really pay attention and notice what you really love about each person.
"Look up to the sky and pause. In the stillness, we can find a new sense of wonder. We need it to recharge, re-balance and appreciate our lives."