How to Become a Leader on the Football Field
Teach by example. Before you start giving speeches to the team, advising anyone else on how to train, or otherwise assuming any leadership roles, first try to lead the team by example. Make sure that every moment that you train, practice, and play is a moment that you'd be proud to have your teammates emulate.
Build camaraderie with your teammates. If you want to lead your football team then you first need to befriend its players.
Put in the extra effort that's necessary. In order to truly be a qualified candidate to lead your football team you must first demonstrate to your coaches and teammates that you love the game. Do so by watching film, lifting weights, running, and constantly being on the lookout for extra time you can put into your football game.
Help your teammates. Watch during practice and see who needs help, then offer it to them after practice.
Act the part. No one is going to believe in you as a leader if you don't first believe in yourself. If you're confident and go about things acting like a leader, your teammates will respond well on the football field.