別府大分毎日マラソン
Thys was born in Prieska, Northern Cape. He represented South Africa in the marathon at four consecutive editions of the World Championships in Athletics from 1999 to 2005. He has also competed at the IAAF World Half Marathon Championships on three occasions, highlighted by top six finishes in 1997 and 1998. Thys is a two-time winner of the Beppu-Ōita Marathon and his time of 2:08:30 set in 1996 remains the course record. He was also a cross country runner earlier on in his career and was the 1994 winner of the Chiba International Cross Country.