Take coal or gas and set fire to it (energy), convert that energy to electricity (energy), turn on a switch at home and the heater comes on (energy).
In the industrialised world, using unsustainable fuels were the norm. Then they built huge power stations like this one at Huntly. After all you need energy to make energy.
Nowadays we have more and more clean options like wind or geothermal, which is even more amazing.
On cold winters days like today’s. I am really thankful for modern energy.