Son enlisting soon, can he choose his NS vocation and does it matter?

Served, and now watched two nephews go through it, so here is the practical picture. He cannot fully choose, but he can influence. Vocation is decided based on his PES (fitness/medical grading), aptitude, the SAF/Home Team manpower needs, and sometimes his own preference if he qualifies. During BMT there are chances to indicate interest and to try out for things like commando, guards, or to be selected for command school (specialist/officer) if he performs well. So the honest advice: if he wants a shot at a vocation he likes, he should get fit BEFORE enlisting, because higher fitness opens more options and command roles. Does it matter? For the 2 years, yes, it shapes his daily life, some vocations are tougher/outfield, some are more routine. For life after, a command appointment (sergeant, officer) does build leadership he can put on a resume, but honestly employers care more about his studies and character than his vocation. Tell him not to over-stress, whatever he gets, the experience shapes him. But do get fit early, that is the one lever he controls.