Sometimes we all need a little encouragement! Especially athletes during a difficult practice or challenging game. Whether you are on the field with them or sitting the bench make an effort to cheer your teammates on. Tell them they are doing a great job! Encourage them and motivate them to try their best and applaud them when they do.
Cheering on your teammates makes your team stronger. Everyone needs to feel like a vital part of the team in order for a team to compete at its best.
Make an effort to say something encouraging to every single one of your teammates. Throughout the season be sure to cheer on all your teammates. Thank your coaches and your captains, but also be sure to encourage those on your team who maybe don't play as much, or who are a little more quiet than the others. Sometimes those who are less confident will blossom right in front of you if you simply give them encouragement and praise. Also remember that cheering on a teammate doesn't have to be verbal! You can give a high-five or even a big smile and applause. If you really wanted to drive this idea home, you could organize a "secret santa" type of activity where everyone chooses a teammate's name out of a hat and commits to encourage that one person throughout the season.
At the end of every game or practice, simply let one person know they did a great job. Make sure and cheer on a different teammate each time!
Check out this website devoted to articles on sports team and coach motivation.
Read this article about why it is important to build team spirit.