How to be an AFL player?

i really want to be an AFL player. I play aussie rules in U 14's and i am a ruckman/forward. sometimes i am back but yeah back to the point. please tell me how to stay healthy and please please please answer this.. HOW DO I JUMP HIGHER IN RUCK? i am tall, shorter people are up in the ruck against me yet i still lose the contest. i have HUGE legs for my age but tell me how can i jump higher. also tell me what i should eat. and how can i stick to it? i do it for a week then i just eat normal again.. :( also what exersises should i do to stay the whole game? please i really want to be one. i suck at school, i try but it doesn't work out. i will get an education but i hope i get into AFL. my cousin is soon going to be in calder cannons and he plays all the same places as me. please guys help me. i am in need :( and also. i need my stamina and endurence up. when i am playing i get tired and walk on the field which makes me week. how can i prevent that? please help me guys! thank you!