Does this not exhaust you? Do you not sense a feeling of fatigue and weariness wash over you? Do you ever stop to think about the effort involved in being that relaxed and limp? The thought and care that went into finding the exact right posture to collapse into?
What he probably thought just prior to this picture:
"Boy oh boy, am I ever tired! I've been up for a whole hour, and I've eaten and played with my fleecy toy. I could really use a nap! Wait - what's this? One of my people has decided to nap without me! This won't do! I must involve myself somehow! I'll just . . . . make the leap up onto this couch, aaaaaaaaannnnnnddddd make my way over to this nice cozy spot on her stomach. *flop* Whew! That was tough! Now to sssssttttttrrrreeeeettttccchhhh out, and - go limp!"
There is absolutely nothing more tiring that watching a cat sleep. I'm feeling . . . . strangely tired now...