Simply put, soccer is a game of fitness, so it is important to be in the best shape possible. Being fit for soccer will allow you to do 3 things that will benefit both you and your team.
1. Being Fit Lets you Play the Whole Game with Limited Substitutions
Soccer games played at the highest level only allow for 3 total substitutions for your team; other levels will impose different limits. This means that if you are a starter, you need to be fit enough to play the whole game. You also want to be fitter than your opponent to constantly beat him/her to balls and be able to make run after run as the game winds on and players start to get fatigued.
But this point isn’t just for the starting eleven. If you are not a starter, you still need to be fit enough to come off the bench and bring energy, enthusiasm, and help change the dynamic of the game. This could mean either closing a game out or creating a spark to help change momentum.