So, where were you when a speck of yellow in a flurry of wheels crossed the cobbles of the Champs-Elysees on July 29, 2018? That was the day Geraint Thomas became the first Welshman to win the Tour de France.
Or do you prefer to remember the former Maindy Flyer's mic-drop after his winner's speech, or the sheer magnificence of his epic stage victory on Alpe d'Huez a few days before?
His ride into Cardiff Castle later that summer was a little more sedate, but the crowds that flocked into the city that day made it just as memorable.
By that point in the decade, of course, Wales had got used to celebratory home-coming parades.
Perhaps your own highlight was the afternoon of July 8, 2016, when Chris Coleman and the Wales football team inched through crowds keen to give thanks for their astonishing achievement of reaching the semi-finals of Euro 2016 in France.
Or maybe your own highlight had come during the tournament itself - whether you watched at home on TV, or in a bar, or on Pontcanna Fields' fan zone in Cardiff as Hal Robson-Kanu bamboozled Belgium with his jaw-dropping Cruyff turn and goal that turned the quarter-final.
It was a goal so good it spawned its own frame-by-frame T-shirt.
Or maybe your moment is that simple, intense feeling of joyful fulfilment in the bars around Bordeaux on the night Wales beat Slovakia, 2-1 - witnesses to Wales' return to tournament finals after 58 years. What bliss it was to be a single brick in the solid Red Wall.
But for pure, unrestrained elation, there can be few moments that compare to a teenage Jade Jones hurling her head guard into the air and skipping around the mat after winning taekwondo gold at the London 2012 Olympics. She had just beaten China's Hou Yuzhou in the final.
Unless, that is, you're more of an admirer of the competiveness of a true champion. In which case you may prefer to recall the Head Hunter's defence of her Olympic title four years later in Rio de Janeiro - when she beat the Spaniard, Eva Calvo Gomez.
Two Olympic gold medals isn't bad and Jones also won a world title this year, to set alongside European golds in 2016 and 2018.
But if gold is the colour that moves you, then it could be you've more of a glint for Aled Davies - the precious metal collector of the decade from a Welsh perspective.
Take your pick. There was his gold at the Paralympic Games of 2012 in London in the discus, followed by his title triumph in the shot put in Rio four years later. Or, it could be one of the six other gold medals he won at three World Para Athletics Championships across the decade.
And if you need that one defining moment, how about his European gold in Berlin in 2018? His leg brace snapped, but he simply taped up the broken pieces himself and won again.
If you enjoy those triumphs over pain and adversity, then maybe Sam Warburton's lifting of the Six Nations trophy, with his one good arm, in 2012 was more your thing.
The Wales captain was injured against France, but that didn't prevent him or Warren Gatland's team from winning the first of two Slams in this decade - the other coming this year.
It was also redemption for Warburton's sending off against France in the 2011 World Cup semi-final - although, for some, not even Dan Biggar's match-winning conversion that beat England in the 2015 World Cup, or the surge to the semi-final again in this year's tournament, can truly make amends for the missed opportunity of 2011.
Maybe a Welshman in a Lions shirt was your pick. You could point to Alun Wyn Jones' leadership triumph in the deciding third Test against Australia in 2013, or the man-of-the-series efforts from Jonathan Davies in the shared series against New Zealand in 2017.
Then, there have been the single moments that have gone around the world - such as the sublime approach chip from Welsh golfer Jamie Donaldson that landed near the flag to clinch the 2014 Ryder Cup for Europe at Gleneagles, or the gravity-defying overhead kick that Gareth Bale produced to enable Real Madrid to win the 2018 Champions League final against Liverpool.
Then, there was the goal that decided football's biggest financial prize - the Wembley play-off final clincher from Scott Sinclair that took Swansea City into the Premier League in 2011 in a 4-2 victory over Reading.
Or the wave from manager Malky Mackay that signified Cardiff City's Championship title and promotion in 2013, or Neil Warnock's double fist-pump that celebrated the same thing in 2018.
Or if football changes on moments, how about the saves produced by Laura O'Sullivan for Wales against England in 2018 that took her team on a journey that ended just short of the World Cup finals, but changed the profile of women's football in the country.
Still not convinced by any of that lot? Then try these: the Paralympic gold medals of Mark Colbourne and Josie Pearson in 2012; Non Stanford's world title triathlon triumph in 2013; the Commonwealth Games golds of Frankie Jones, Natalie Powell, Jazz Carlin and Georgia Davies in 2014, then Alys Thomas ; Elinor Barker's gold at the 2018 Gold Coast Games; Hannah Mills' sailing gold at the Rio Olympics; the same colour by cyclist Owain Doull in Rio.
Or how about Becky James' four gold medals at the world track cycling championships in 2013; the night boxer Lee Selby became world champion in 2015; the Cardiff Devils' triple of 2017; Laura Deas first Welsh Winter Olympic medal in 2018; or Mark Williams rolling back of the years to become world snooker champion again last year.
But if it's romance and tears that move you, then how about this.
Gilbert Miles, who was 72 at the time, had one bowl left to make sure Wales got a medal in the mixed B2/B3 pairs, for visually impaired competitors, at the Gold Coast Games in 2018.
He asked what the line was, drew a deep breath, and rolled the perfect bowl to get Wales onto the podium.
Of course, all this activity - and the memories they provide - are no accidental. There has been organisation and support behind the drama, something Brian Davies, acting chief executive of Sport Wales, is quick to acknowledge.
"It has been an era of unprecedented success," says Davies.
"Thanks to their talent and dedication, Welsh athletes and coaches have created so many highlights that will live long in the memory. Whether you watched the drama unfold in person, or were glued to your TV screens at home, everyone will have their own standout moments that they enjoyed.
"While reflecting on all of those moments, and looking forward to the future success that we hope is to come over the next decade, it is important to remember the significant impact that the National Lottery, alongside Welsh Government support, has had in supporting Welsh sport.
"Since it began in 1994, £309m of National Lottery money has been invested into nearly 26,000 sports projects in Wales. The vast majority of those projects are in communities across the country, delivering grassroots sport to people in their local areas every day of the week, enabling everyone to enjoy the benefits of sport wherever they are.
"The generation of athletes who achieved so much during the last ten years enjoyed the fruits of that huge investment, from better grassroots opportunities right up to world-class facilities such as the National Pool in Swansea, the National Indoor Athletics Centre in Cardiff, and the National Velodrome in Newport - all which were funded thanks to the National Lottery.
"Without the National Lottery players and their support for sport, much of our recent success wouldn't have been possible and grassroots sport in Wales wouldn't have the positive impact that it does."
Sport Wales are currently inviting sports fans up and down the land to help decide the most memorable moment in Welsh sport over the last decade. Look out for the #WelshSportDecade cup competition which is being played out on Sport Wales' twitter, facebook and Instagram accounts during December.