Making a snowman is always a big ball of fun - three snowballs full of fun, to be exact. And each snowball starts out small, getting bigger as you roll it in white fluffiness. Let's imagine that you go outside in a fresh snowfall to build one of these guys, but you don't have the best-suited yard for rolling snowballs. In fact, your backyard is one giant hill. This hill is fantastic for sledding, but not so much for making snowmen. Anyways, in order to make a giant snowball for the snowman's bottom, you'll need to actually push this snowball up over the hill and then down the other side. You do it because it's fun - but make no mistake, it takes a lot of energy to get started up this hill. This is hard work. Right now, you share a quintessential problem with some chemical reactions within a cell. These chemical reactions might be a lot of fun when you're in a cell, but it takes a lot of energy to get them started. This is called the activation energy, or the energy required for a reaction to start. You can think of activation energy as that energy you needed to muster up in order to push that snowball up and over the hill in your backyard in order to maximize the size of your snowball and get it to the other side. What your cells have to help overcome a problem of high activation energy are called enzymes. Enzymes are proteins that lower the activation energy of a reaction. In doing this, enzymes increase the rate of a reaction, helping it to occur faster. However, enzymes are not consumed in a reaction; they simply help it to occur. They do not add snow to your snowball; they just make it easier to make a snowball.