Identifying a career in health and fitness?

I'm going to school and am deciding on a major. I am leaning towards something in health and fitness. I've considered dietetics, nutritionist, personal trainer, things like that. Are there careers that have a combination of those needed skills? What majors open up those careers? Identifying a career in health and fitness?I been reading a lot about combining physical fitness and brain fitness as an up and coming thing good luck.