Energy can exist in different states. Potential energy is the energy that an object has due to location or position. A bowling ball being held high in the air has potential energy because it has the potential to do work.
Kinetic energy is energy that an object has due to motion.
Chemical energy of food consumed by living things, is a form of potential energy. When living things use potential energy to do work they convert it into kinetic energy.
When Fred runs up a flight of stairs he is converting the potential energy in his body into kinetic energy.