Dear Peggy, You are indeed in a difficult situation. I'm glad to hear that you considered the physical strain of a career in massage in choosing your work options. As you accurately noted, giving massage full time is hard on the body. Anyone who isn't sure she can make that commitment is wise to think of alternatives to a full-time career in massage. In a part-time career, these challenges are even greater.
Massage can be a great career, but it can also be a difficult one.
Take a massage-related second job instead of an administrative job. You could try teaching massage. Or you could train in a bodywork technique that is less stressful to the body than Swedish or deep-tissue massage, like Reiki, Feldenkrais or Trager work. Offering spa modalities like aromatherapy or hydrotherapy can also greatly enhance your income and bring in enough clients to boost your income to a full-time level. You really have a good number of options left to explore.