As I was walking up a very steep hill this morning, I devoted my remaining oxygen to calculating my energy output. Once fully oxygenated, I rechecked the numbers and came out with a work output of 168 watts. This figure is just the energy to lift me up the 170 foot rise over 2 city blocks (10 % average slope as it turns out).
So how does this relate to energy, and its inherent value ? If I worked at that energy output rate for 40 hours per week, 52 weeks per year, for 5 years, I would have produced 1,747 kWh. As it turns out, a barrel of oil contains about 1,700 kWh of energy (if transformed at 100% efficiency).
Reference: Barrel of oil equivalent