The ERG (existence, relatedness, growth) theory (Clayton Alderfer put forth this ERG theory) can be used to explain someone's motivation to work in a prior job they have had. Using myself as an example, ERG theory pertains to my earlier experience as a baker in the supermarket industry in the 1980's and early 1990's.
Concerning the existence factor, this job satisfied my physiological and safety needs. In the baking business, the job satisfied my need for basic human survival in that it provided me a safe, professional, monitored, stable working environment that provided me a good income to meet my needs for food, clothing, accommodations, and such.
Pertaining to the relatedness factor, the job as a baker satisfied my social and external esteem needs. The job allowed me to grow in a career and further my skill set, which I could apply to future jobs. It also furthered my income-earning objectives. Baking in a supermarket environment with other bakers, cake decorators, and such fulfilled my social needs as I interacted with different people on different baking projects.
As relates to the growth factor of the ERG theory, my job and responsibilities as a baker helped me achieve my self-actualization needs. I prospered in a job that allowed me to use my talents to create food products that consumers could enjoy.
I took pride in creating tasty baked goods each working day. I contributed to the success of the supermarket and met the needs of my customers. This, in turn satisfied my internal esteem needs; I felt good about what I accomplished and looked forward to new challenges in the industry to better myself.