Mike grew up in Southern California and swam competitively, starting at age 5. By high school, he had already broken onto the national scene as a top age group swimmer on the Irvine Novas Swim Team. At 14, he joined the world renown Mission Viejo Nadadores swim team to train under Olympic Coach Mark Schubert and alongside many of the world’s top swimmers. Mike rose to the top of US distance swimmers and won his first of five US National Championships at the age of 17.

In 1984, Mike won the Olympic Gold Medal in the 1500-meter freestyle at the Los Angeles Olympic Games. Not long after, he attended the University of Southern California and went on to have a stellar post-Olympic year, winning two NCAA titles, five US National titles, and two US Open/American Records.

Following his graduation from USC, Mike worked in real estate and then insurance and worked as a television color commentator for swimming and triathlon events. In 1992, he was the NBC Sports color commentator for the Barcelona Olympics. He also coached a competitive swim team in Newport Beach and assisted the college team at UC Irvine in his spare time.

In 1993, Mike completed the Hawaii Ironman Triathlon on only six weeks of training while working as a race reporter for NBC. He finished the race in 13 hours and 41 minutes and set the dubious record of fastest swim/slowest overall finish.

Around the same time, Mike watched his three year-old son, Ian, learn to swim. The experience of watching his son and other children learn to enjoy the water led Mike to pursue a career change and establish Mike O’Brien Swim Instruction.