Captain Mick; your advice is pathetic.
Naturally in order to be selected and qualify for an airlines' cadetship/sponsorship scheme you need good/excellent grades and health and fitness.
For someone who is 15/16; it is imperative to focus on your priorities being school; and getting good grades. Simultaneously; get yourself involved as much as you can. I was a school vice-captain at my school. You need to show leadership qualities. In such a highly competitive process; every point counts; palpably; so getting good grades is important. Although; those alone will def not guarantee you a place on a cadet program. There not looking for rocket scientists; just highly motivated people who have got the brains; and are willing to have a beer at the end of the day. At the end of the day; its those that want it the most that get it.
I dont suppose you got into a cadetship did you.
Your advice; considering you have 8000hrs under your belt; might not be the most precise and relevant. Things continually change; today it is even more competitive than 10 yrs ago; hence it is wise to talk to people who have recently done the training program; and made it through.
For those aspiring youngsters; aviation is a competitive industry; dont believe everything you hear. From posts I've read; you can tell there lots of shannanigans around.
cheers