1. Become a cat.
2. Become lazy, if you are already a cat.
3. Get yourself adopted by some humans who have this fabulous invention called "central heating" where hot air comes out of walls at - get this - cat height.
4. Find a sunbeam on top of a comfortable sleeping surface (this can be anything from an unmade bed on the floor, fabric, or a pile of books and papers. Your choice.) It's best when this comfortable sleeping surface is strategically located directly across from that thing that spews out hot air, what humans call a vent.
5. Expose as much of your body surface as possible to the sunbeam for maximum absorption. This works best if you are a ridiculously fat cat.
I hope you liked my tutorial.