[GroksBarnacles]

Friction. Work isn't just about height.

[thfuran]

Holding that block stationary at arms length then. 0 work.

[dotancohen]

Put that block on a shelf at the same height. 0 work.

The fact that your muscles burn ATP just fighting gravity is a feature of biology, not fundamental to the physics involved.

If you want to read about another similar example, Google for rocket launch gravity losses.

[thfuran]

I think you're missing the point. A lot of basic mechanics actually isn't especially intuitive because things like work simply do not map well to everyday experience. I'm not suggesting that work is defined incorrectly or something.

[dotancohen]

I see what you're saying now, and I agree.