What it takes to be a marrine?

So i really look up to millitary personel and what they do for our country and how honorable they are and i really want to be one of them one day. But if i join i want to be the best and being the best to me means being a marine. I've been researching this for a while and as much as i'd love to do this for myself and my country im still a bit apprhensive. I'm honeslty just concerned i wont meat up to the grueling physical requirements. So what does it take? Does anyone have any suggestions on how to get more prepared and physically fit for boot camp? Please if you've served as a marine any of your input and advise would be much appreciated! Thankyou!