I thought it was pretty funny, Garfield blaming the basic Newtonian laws of physics for his personality flaws.
But what kind of set-up is "Why don't you move around more?" Yes Jon, cats are great, and most of the appeal is how much they move around. Cats are notorious movers-around. The motivating factor behind most pet purchases is to watch an animal move around. And why doesn't Jon stick around to "hear" Garfield's answer? Some days even dealing with your cat's non-verbal sassing is too much to bear.
In continuity news... I loved the July 8 strip, but that was seriously how the Vet Appointment Disaster storyline ended? Well, I guess Garfield is a fine portrayal of human courtship. Weeks of buildup and nerve-aggravating excitement... then he tries to tell the girl how he feels... then she walks away. Then he goes home and vents by complaining that his cat doesn't move enough.