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There's a concept in science called gravity. You may have heard of it. It basically it the force with which you are stuck the ground.

You knew that but I started with it to prove a point. First, that shouldn't waste your time reading the intro paragraphs. And second, that you already have one giant force holding you down. So every day of your life you've pushed against it. That is to say, you can and are fighting, no matter how small or inconsequential the punches you land may be.