Being in top shape will separate you from the rest when try-outs come in the spring. No matter how good your stick skills and game sense is, it will be meaningless if you can't get up and down the field throughout an entire game. High school lacrosse seasons generally begin in late March or early April, with preseason starting in late February. With this in mind, you should start conditioning for your season on your own in the fall, or December at the latest. It is not enough just to go to captain's practices, you need to train on your own as well so that you stand out when preseason starts!