Lacz started BUD/S Class 245, but suffered a back injury that forced him to roll back to the next class. He went on to graduate with BUD/S Class 246 in 2003. As a Hospital Corpsman, Lacz also attended 18-D Special Operations Combat Medic School at Fort Bragg before checking into SEAL Team 3 in Coronado, California. Soon after, he attended Army Sniper School and returned to Charlie Platoon where he began preparing for his 2006 deployment with Chris Kyle, Jonny Kim, Marc Alan Lee, Ryan Job, Jocko Willink and Mike Monsoor (who was in the same Task Unit, but from Delta Platoon).[2]
In 2006, Lacz deployed to Ramadi, Iraq, with Charlie Platoon, Task Unit Bruiser.[1] The work he did as a platoon sniper and medic contributed to his task unit becoming the most highly decorated special operations unit of the Iraq War.[4] Lacz personally conducted numerous sniper overwatches, direct action missions, raids, and tribal engagements in support of the effort to halt the spread of violence through Ramadi. For his actions on his 2006 deployment, including acquiring numerous enemy kills and braving enemy fire to carry a fallen comrade to safety, Lacz was awarded a Bronze Star Medal with a Combat 'V.'[1]
In 2008, Lacz returned to Iraq, this time as a member of Delta Platoon. Joining Chris Kyle for another deployment, his focus was the Iraqi border with Syria and the interception of foreign fighters trying to infiltrate the country.[3]
As a SEAL, Lacz gained extensive experience in Special Operations Combat Medicine (SOCM), Special Operations Dive Chamber Medicine, Military Free-Fall HALO and HAHO Operations, Long-Range Target Interdiction Sniper work, Survival Evasion Resistance Escape (SERE) Training, Battlefield Interrogations, Close Quarters Combat (CQC), Counter-Terrorism Operations, and Naval Special Warfare Lead Breaching Operations.[5]
Because of his close working and personal relationship with Chris Kyle, Lacz was asked to contribute to his autobiography, American Sniper, through interviews. Kyle also discussed Lacz frequently when referencing the 2006 and 2008 deployments (as "Dauber"), laying the groundwork for Lacz's involvement in the production.[8] He was hired to provide SEAL technical advising for the film. Bradley Cooper also convinced Clint Eastwood to allow Lacz to audition for the role of "Dauber," after which he was cast to play himself.[9]
Lacz is the spokesperson for Hunting for Healing, a 501(c)(3) charitable organization he founded with his wife, Lindsey. After taking a trip to Africa together in May 2015, the couple decided to launch a charity with a mission to take service-disabled veterans and their spouses on hunting, fishing, and outdoor excursions.[10]
Currently, Lacz works as a physician assistant in northwest Florida and southeastern Alabama, where he is co-owner of Regenesis, a lifestyle and performance medicine medical practice.[13] His past military service influences him greatly as he also seeks to actively support service members and veterans by tending to their medical needs.