Select a measuring cup or heat-proof bowl large enough to hold the drippings. Line it with a zip-lock bag of comparable size. Set a strainer over the bowl. When your roast comes out of the oven, transfer it to a platter. If you normally deglaze your pan with wine or some other liquid, go ahead and do so, scraping up the brown bits from the bottom of the pan. Pour the drippings through the strainer into the bag-lined bowl. Wait a minute or two to allow the fat to rise to the top. Lift the bag and hold it so that 1 corner tilts down toward the bowl. Notice that you have 2 layers: a juice layer on the bottom and a fat layer on top. With a long sharp skewer or narrow-tipped knife, poke a tiny hole at the very tip of the lower corner and allow the contents of the juice layer to run into the bowl. As soon as you reach the end of the juice layer, TILT THE BAG AWAY FROM THE HOLE, and discard the fat layer left in the bag. Your bowl should contain nothing but beautiful, healthy juices, and you can proceed with your recipe as you normally would.