The 27 year old Dunedin runner had not planned on running any more half marathons this year, but changed his mind when the opportunity to run the Incheon Songdo International Half Marathon arose.
It is an invitation only race, and Shields got the chance to compete when event organisers contacted Athletics New Zealand asking for two male athletes.
Shields and former Otago runner Callan Moody, who is now based in Christchurch, applied and were selected.
Organisers are covering the cost of flights and accommodation for the pair. Shields will leave for Seoul next Thursday.
Shields admits he does not know much about the race, but is looking forward to hitting the flat and fast course.
''I don't know too much about it. The website is in Korean,'' he said.
''I had a look at the You Tube video of last year's race and it looks pretty flat and fast. I'm not sure how many countries they are opening it up to.''
One thing Shields knows is that it will be warm. The temperature in Seoul hovers around the 30degC mark this time of the year.
He has been doing ''a bit of heat training'' to prepare for that, including running with extra layers.
Shields, who was born and bred in Dunedin and attended King's High School, did not run the Dunedin half marathon earlier this month, but recorded a personal best time at the national half marathon championships in Christchurch in May.
He clocked 66min 32sec on his way to sixth placing, 1min 19sec behind Moody, the winner.
Shields also ran the Gold Coast half marathon in July, when he crossed the line 10th in a field of more than 10,000 runners.
He stopped the clock in 67min 38sec, while Moody was fifth in 65min 54sec.
''I got a bit ill after the Gold Coast run, but the last month of training has been quite good,'' Shields said.
''I wasn't planning on running another half this year, but this one popped up and I couldn't turn it down.''
Shields works fulltime as a physio at Physio Performance in Dunedin, and aims to run between 70min and 90min a day.
He plans to hit the track when he returns from South Korea to prepare for the Zatopek 10 - a 10,000m invitation only race for elite runners - in Melbourne on December 5.
The event doubles as the Australian 10,000m championships and Olympic trial.
