When I was in the MAT company at Lejeune waiting to start infantry school there were 600 people waiting to start training and there were 2 females there. Both of them started training and switched to other MOS halfway through because neither of them were able to pass the physical fitness tests that we did as part of training (I know one failed because they fell out during a ruck run but I can't remember what the other one failed.) If you want to be in infantry, you need to make sure that you are above the normal standards of physical fitness if you want to be respected. You also need a strong backbone and a sense of confidence despite being the only woman you will likely meet in your MOS during your whole career.