In the high-pressure corporate world, Tony Thomas says running is like medicine.
''It's a head-clearer," he said. ''It's probably the only time I get to not think about anything.''
He runs three or four times a week before heading to work as the group marketing director for DMG Radio.
''I run first thing in the morning before everything goes a bit crazy,'' he said. ''I have a lot more energy and I'm able to concentrate for longer.''
He has crossed the City2Surf finish line ten times - the fastest in 54 minutes - and next month he will be running for the Cancer Council.
David Giffin agrees a morning jog is the best start to a day in the office, improving productivity.
''You've done something positive and you're feeling good about the day ahead,'' he said.
The former Wallaby now works in institutional banking at the Commonwealth Bank.
He will enter this year's City2Surf primarily to raise money for the Redkite charity, which supported his family during his son's cancer treatment.
Shortly after he retired from rugby union in 2004, his two-year-old son was diagnosed with neuroblastoma. Redkite connected the Giffins with other families coping with cancer.
''It really is a unique experience and we found that to be able to share that with others is very valuable,'' he said.
His son was treated for eight months and is now a healthy 10-year-old.
Damien MacRae will be running alongside about 1000 colleagues from Westpac.
"When I go for a run in the morning, I get into work and I'm definitely more prepared for the day ahead," he said.
There are countless benefits to running, according to Aaron Coutts who is an associate professor in sport and exercise science at UTS.
''There's a clear increased physical capacity, stronger heart, healthier heart, decreased cardiovascular risk, decreased risk of metabolic diseases such as diabetes, decreased body fat,'' he said. ''And also there are psychological adaptations that occur - improved esteem and concentration, and decreased stress.''
He said it is "absolutely essential" to find a small break in the day to get outside and exercise.
The physical activity itself can also directly improve workplace performance. He said a recent study showed as little as one or two hours of fitness a week can make a significant difference.
''When you're physically stronger and healthier your psychological stresses are reduced,'' he said. ''You can't extract the physical from the psychological.''