Major General Lars S. Lervik started his military career at the Cavalry Officers Candidate School in 1990 and served in the Armored Battalion at Setermoen until he started at the Norwegian Military Academy in 1992. After graduation from the Military Academy in 1995, he served as platoon leader, squadron 2iC, S-1 and squadron commander in the Armored Battalion at Setermoen.

Following a deployement as S-5 in NORBN/ KFOR IV (Kosovo) in 2002 – 2003, he served as a military instructor at the Cavalry School and as the military assistant to the Chief of Staff of the Norwegian Army. In 2005 – 2006 Lervik deployed as the Chief of Staff in NOR BG 3/ ISAF (Afghanistan). He has also served as the 2iC in the Telemark Battalion and as the G-3 in Brigade Nord.

In 2009 he commanded the Armored Battalion at Setermoen and following this he deployed as the Chief of Staff of the Norwegian Contingent in Afghanistan. Lervik commanded the Telemark Battalion at Rena between 2010 and 2013, including a deployment to Afghanistan as commander for NOR PAT/ ISAF in 2013. Between 2013 and 2018 Lervik served in the Department for Security Policy and Operations in the Norwegian Ministry of Defense in Oslo. This includes service as the Assistant Secretary General in charge of national security policy, crisis management and readiness from 2014 (FD II2). From 2018 to 2020 he commanded Brigade North. 25th June 2020 he assumed command over the Norwegian Army.

In addition to military education in Norway, MG Lervik has attended the Armor Captain Career Course in Fort Knox (USA), Advanced Command and Staff College in Shrivenham (The United Kingdom) og U.S. Army War College in Carlisle (USA). He has a Master of Arts in Defence studies from Kings College in London from 2007 and a Master in Strategic Studies from US Army War College from 2017. In 2020 he was appointed as a fellow to the Royal Swedish Academy of War Sciences.