Simon grew up in Melbourne, Victoria, and attended Xavier College. He joined the army when he left school and attended the Australian Defence Force Academy, Australian Capital Territory. Simon decided to leave the academy after a year and traveled around Australia taking various jobs in the hotel industry before returning to the army. He was accepted into the Royal Military College at Duntroon, Australian Capital Territory, for training and graduated from Duntroon at then end of 1995. Simon was then posted to 1 Royal Australian Regiment (RAR) in Townsville, Northern Territory, and completed regimental officer basic training at Singleton. At this time he commanded a rifle platoon of 20-30 men. At the end of 1998 he was posted as a liaison officer to a new brigade commander, Brigadier Mark Evans. Simon joined the Ready Deployment Force - 3 RAR with his brigade commander and was posted to 1 Brigade in Darwin, Northern Territory. The brigade was sent to Dili, East Timor, in September 1998 and he served there working with the United Nations for over a year. When Simon returned to Australian he was posted to the Melbourne University Regiment, Melbourne, Victoria.