It can be hard to always remember to hydrate throughout the day. We all get busy, or figure that a glass or two to quench your thirst will be enough. But keeping your body fully hydrated is a vital part of staying healthy, both inside and out.

The Mayo Clinic advises that men drink about 15.5 cups (3.7L) of water each day, and 11.5 cups (2.7L) for women. While this may seem daunting at first, fortunately we get about 20% of the daily water intake we need from foods and other sources, plus you can space this out across the day. While the classic “8 glasses a day” is a good goal to aim for, this can vary depending on multiple factors, including body mass, your existing exercise regimen, and more.

But why drink so much, you may ask. Water is an essential part of the body’s functions, perhaps the most essential. Every single cell in your body requires it, with more than half of your body’s weight being attributed to water. It purges the body of waste and contaminants, protects your body’s important tissues, keeps joints smooth and regulates your body temperature, all imperative factors for a long, healthy life. Additionally, staying hydrated keeps your skin moisturized and smooth, keeping wrinkles at bay and pores clear of gunk that could lead to skin infections.

Two good factors to make sure you’re drinking enough are to gauge how thirsty you feel, and to see if your urine is clear. While the latter may seem odd, this is an excellent indicator to make sure if your body has been purging contaminants from within.