When I decided that tournament chess -- particularly weekend Swiss-system tournament play -- was not really compatible with what I wanted to do in running, my choice between the two was (as I recall) an easy one. Chess was something I was pretty good at (and did enjoy a great deal, at least outside the tournament arena), but running was something that I was passionate about. I went with the passion.
I also preferred the identity of a runner. I think it was better for my self-esteem to see myself (and to be seen by others) as more of an athlete, and less of a geek. Also, running was a pretty cool sport in American society during the late '70s and early '80s; the people who showed up at road races seemed generally to be healthy, happy, and well-adjusted, and there was a good mix of male and female runners of all ages. Tournament chess players, on the other hand, were overwhelmingly male, and often socially marginalized.
Both activities were very important to me at various times in my life, but chess was easier to put on the shelf. I expect that I will always see myself as a runner and athlete.