The changes in lifestyle that came with the modern age were mainly due to the invention of the steam engine and later related inventions.
With the Industrial Revolution, the developed part of the planet became more and more easy to convert the energy of wood and fossil fuels into motion, and was thus less dependent on the energy it drew from food to do its work. More and more work has been done by man with the help of machines and devices.
It is precisely because of these changes in the exploitation of energy that gradual changes have taken place in man's consciousness regarding the awareness of the importance of his own energy. Before the industrial revolution, the most important thing for survival was to be physically efficient enough and able to do everything necessary with as little effort and as much imagination as possible. If a man used more energy than he gained then he was in big trouble and his survival was threatened.