Line a fine-mesh strainer with cheesecloth or a large coffee filter and set it over a large bowl. Spoon the yogurt into the prepared strainer, transfer to the refrigerator, and allow the whey to drip out until the yogurt has thickened to your desired level. Transfer the strained yogurt to a sealed container and keep refrigerated. You can drink the whey or use it in some baked goods or other preparations.