Walter Nernst, famed for his formulation of the third law of thermodynamics -- from which it follows that, in a closed system, the amount of energy available to do useful work decreases (as heat is produced) and that, therefore, the 'entropy' (thermal energy) of the universe continually increases -- once began breeding fish in a pond near his cottage. Some time later, a friend asked him why he bothered, adding that even poultry-breeding seemed interesting by comparison. "I breed animals which are in thermodynamic equilibrium with the environment," Nernst replied. "Breeding homeotherms just means warming the Universe at your expense."
[The Third Law of Thermodynamics states that the entropy of a pure perfect crystal at 0 Kelvin = 0.]