Without any additional education, and assuming you are in the USA or Canada, you could potentially work as a personal trainer. We do have insurance partners in the USA and Canada that will insure a professional with this credential alone (see below). However, we would recommend starting with the Certified Personal Trainer (CPT) certification. The HMS credential was designed to be an additional or advanced credential focused on optimizing movement with corrective/therapeutic exercise.
Liability insurance partners:
United States - insurefitness.com/partners/brookbush
Canada - www.ineedapolicy.com