The carbon cycle refers to the procedure in which the atoms of the carbon are recycled again and again on Earth. Carbon recycling occurs within the biosphere of the Earth and between the nonliving environment and living things.
In case if I were a carbon, then I would have originated from fossil fuels and left the ground, through the process of photosynthesis I would have entered the trees, I would have consumed by animals, even I would have released from some of the trees or plants that dies, I would have also released from animals by the process of decomposition after their demise, and animals can even breathe me in out by the process of respiration.
I believe it would be less ATP generated during cellular respiration. This is because Mitochondria are the "generators" of the cell, and create ATP (which powers the cell's metabolic activities) in exchange for oxygen and nutrients.