We vote because it is our duty as citizens.
We vote because we are privileged to live in a country whose forebears worked hard to get us this right.
We vote because the right to do so gives ordinary people great power: the power to participate in the choosing of who governs. That power may not be absolute, that participation may not be perfect or complete, the results are always going to be mixed, and there may be no final choice we can make that is going to be completely satisfactory to us, but elected governments are still the only place where everyone gets to have an input and where the results are irrefutable by the holders of the reins of power.
We vote because our democracy may not be permanent, and we can only keep it alive and strong by participating in it.
We vote because a democratic election, as flawed and as vulnerable to outside forces as it may be, is still the only arena in which, on election day, the single mothers struggling to feed their children and keep households together and the millionaires in the wealthiest neighborhoods in the country, walk into the same non-glamorous, non-exclusive church halls and school gyms and are handed the exact same piece of paper. No-one gets to make more than a single X.
We vote because voting allows us participate fully in our citizenship, and participating fully feels good.
We vote because democracy is not perfect, but it is right: We all deserve a say, and on this day alone, we all get one.