According to the VFI model, generally there are six different sources of motivation. They are presented here in the shape of a star, as in the illustration below:
Source: Clary, E. G., Snyder, M., Ridge, R. D., Copeland, J., Stukas, A. A., Haugen, J., & Miene, P. (1998). Understanding and assessing the motivations of volunteers: A functional approach. Journal of Personality and Social Psychology, 74(6), 1516-1530.