Farhan Akhtar prepared for Major Shaitan Singh through a mix of physical transformation, military-style training, and acclimatisation in real high-altitude conditions. He has also spoken about immersing himself in the real history and emotional weight of the Battle of Rezang La and its soldiers.​

Physical transformation

Farhan deliberately lost weight to look leaner and closer to the real Major Shaitan Singh, while still maintaining muscle and the bearing of an army officer. He also adopted a crew-cut style and stayed away from public appearances for a period to preserve the authenticity and surprise of his on-screen look.​

Military-style training

For the film, he and other cast members underwent military-style preparation, which included hand-to-hand combat, weapons handling, and drill work to move and react like trained soldiers. The idea was to make the unit look like a cohesive, battle-ready company rather than actors merely posing as soldiers.​

High-altitude acclimatisation

Farhan reached Ladakh around 10 days before filming began to acclimatise to the 14,000-foot altitude and rehearse action choreography on location. He has explained that actually experiencing breathlessness, harsh temperatures, and dust storms helped reflect the real physical struggle of the soldiers in his body language and performance instead of faking it on a set.​​

Emotional and historical immersion

He has said that learning about Major Shaitan Singh and the 120 men at Rezang La deeply inspired him and strengthened his sense of responsibility toward the role. Farhan has described the project as an honour and emphasised that understanding the real sacrifices behind the story was central to how he chose to portray the character.​