The law of diminishing returns (also law of diminishing marginal returns or law of increasing relative cost) states that in all productive processes, adding more of one factor of production, while holding all others constant, will at some point yield lower per-unit returns.* The law of diminishing returns does not imply that adding more of a factor will decrease the total production, a condition known as negative returns, though in fact this is common.
So it's not just the number of hours we sit at a desk that determines the value we generate. It's the energy we bring to the hours we work.
Stress is not the enemy in the workplace. Indeed, stress is the only means by which we can expand capacity.
*Samuelson & Nordhaus. Microeconomics. 17th ed. page 110. McGraw Hill 2001
