Voting is entirely fundamental in a democratic society. Without it, the people have no official way to declare what they think is right.
However, voting is not the only way that you can let your voice be heard. You can volunteer for your party and spread their word. You can call your representatives or sit in on city council meetings. You can boycott or support companies that do or don't support the ideas which mean the most to you. You can go out to the streets and protest or demonstrate when you feel like the government isn't listening to your voice.
No matter the way you let your voice be heard, voting will always be integral to our government's function so let your voice be heard.