You forgot to buy milk. Naturally, it's all the big bang's fault.
Cheeky video essayist exurb1a uses human forgetfulness to explain the concept of determinism. Essentially, it's the idea that because the universe and everything in it follows rules, we all exist in a highly complicated chain reaction that governs everything from the movement of planets to the release of specific chemicals in our brains.
Free will? "Bah!" says determinism.
Did you read this post because you wanted to, or because you were always going to? Don't all frantically check the fridge at once.