First Law of Thermodynamics
In terms of this physical plane, there are no free lunches. Everything costs something; time, money, energy. Often spending one of these things results in the production of another thing to spend. Work either makes or finds sustenance, which in turn provides the very life energy required to work to find sustenance. It is a cyclical process, one known under many names: the circle of life, the life cycle, the tree of life.