For Gruner, it was the occasion to forge himself the heart of a fighter for a forthcoming professional kickboxer career, and to learn the combat and discipline ropes necessary to be a credible action films actor, director, and producer. When he got out of the service, he had developed a sense of "never giving up" and was feeling in his mind that he was indestructible. This is how he has been capable to reproduce for the screen actual combat and fighting techniques, which he had learnt in real life as a Special Operation Forces Commando. This also explains some strange weapons seen in his movies, which are traditionally used by military special forces only, and therefore not usually shown in the film industry.