SINGAPORE - His bare feet pounding the pavement, 37-year-old Ranjith Vijayan hardly breaks his stride as he breezes past joggers at Bishan Park.
But his gaze is not fixed on the path ahead.
Rather, he fiddles with a 3x3 Rubik's cube, unscrambling the baffling conundrum which turns smoothly compliant in his hands - within 30 seconds.
With barely a second thought, he reverts the solid block back into an amalgamation of assorted colours.
Vijayan is far from done though - for come Dec 6, he will have 42.195 more kilometres to run and at least 175 more cubes to solve.
The software engineer will attempt to break the Guinness World Record for the most number of Rubik's Cubes solved at this year's Standard Chartered Marathon Singapore.
The record stands at 175, achieved by American Shane White at the 2012 Rock 'n' Roll Savannah Marathon in Savannah, Georgia. He clocked a time of 4hr 53min 39sec, under the five hours required to make a valid record attempt.
Speaking to The Straits Times, Vijayan said he is confident of bettering White's record and aims to solve at least 300 cubes during the StanChart run.
Solving a solitary cube used to take him nearly as long as the time he now takes to run a full marathon.
The father of two picked up his first Rubik's Cube in 2001 and has since started on "speedcubing", which is to solve a Rubik's Cube as quickly as possible.
He has spent an estimated $1,000 on his hobby, having purchased cubes from Indonesia, Japan and China during business trips.
The mere thought of running a full marathon may leave some feeling fatigued, but Vijayan said it was the monotomy he experienced as a new runner that inspired him to combine his passion for solving Rubik's Cubes with his love for marathoning.
"When I started running (in 2014), I found it very boring," he said. "While running, you can count the trees or count the people or listen to music. But nothing really worked for me.
"I found that by running with a Rubik's Cube, I could run longer distances without stopping."
To him, running and solving cubes simultaneously is not difficult, as he relies on "muscle memory" and memorised algorithms.
His first race with a cube in hand was the Standard Chartered Half Marathon in December 2014, which he finished "comfortably".
Then, the cube was a mere diversion to keep him occupied.
This time, he plans to take it a step further and come race day, he will be followed by a photographer, videographer, two pacers and a helper to hand him "scrambled" cubes.
The support of his family also has been key during his preparations.
Although not a big fan of Rubik's Cubes, Vijayan's wife will be waiting for him at the finish line.
"Sometimes when she gets angry, she will scramble my cubes," he added.
Vijayan's four-year-old son will also be participating in the 700m Kids' Dash event on Dec 5.
Ultimately, Vijayan's record-breaking attempt is to inspire others to pursue their passions and stay active.
He now runs an average of 40km a week, usually training at Bedok Reservoir.
"I used to believe sports and athletics are for a certain set of people," said Vijayan, who admits he has never had much interest in sport.
"I want to prove that guys like me can run marathons.
"Some people don't run because it is monotonous.
"(But) You can beat the monotony of running by doing something you like."