Gao Yang was indeed fortunate—he had come across a retired SBS sniper rather than an active one. It is well-known that service in the SBS is incredibly long, and by retirement, most members are of advanced age. While their experience may be richer, their physical responses and various capabilities have significantly declined.
To join the SBS, the difficulty and length of time required is enough to dismay anyone. The first step is to join the Royal Marines. Upon enlistment, one must submit an application expressing the desire to join the Special Boat Service, which is the only way to qualify for future SBS selection.
First, one must undergo 30 weeks of Royal Marines basic training to become a Marine. During this period, the instructors will observe the performance of those who have applied to join the SBS and make an initial assessment of their capabilities.