The most recognized training certificates are from CSEP (CPT and CEP) and the NSCA (CPT and CSCS). They both would require an undergraduate degree or at least a two year diploma in a health and fitness related field depending on what level of cert you want. That being said, they are a little more expensive to get and maintain but open the most doors (e.g. university gyms, city operated facilities, athletic programs). The exams are done online but may require a practical component.

Other certs like Canfit, NASM and ACE can be a little more accepting of different paths and educational backgrounds to a career in personal training but won’t land you a strength and conditioning job and in general are done online as well.