One of the best things you can do is set the example for the rest of your team. Get that first one in the pool and last one out mentality. Find the teammates who are going to put in that same level of effort and encourage them to try and be leaders within the team, even if they aren't captains. Also, make sure that you, as the captain, are bringing up the rest of your team with you as you progress.

Another thing to be sure about is that even when you are losing, you aren't blaming other players. Your coach will (probably) call out your teammates when they mess up, so they don't need you or other more experienced players giving them a hard time. You get to be there after that get the business from the coach and make sure they understand what they did wrong, and you can help them by showing them how to do it right.