I think it's a profession, a career. More than a job.

My work, some years it was great, other years overwhelming. Now I'm in a role that I really enjoy, feel passionate about, can be an "evangelist" for my craft. It took me a long while to get to this place. There are times when management makes you nuts with changes, and when the people you work with are less than motivated, or you are just tired and need a break. But, underneath you are happy with your work!

A good therapist really loves the job, it is their profession, their livelihood. The good therapist wants to keep improving, see clients grow and change, watch happiness emerge. The good therapist likes earning money doing a job that is so enjoyable.

Semantics -- For me a calling is solely connected with being a religious leader (men and women may be a priest or bishop in my church). It does require that a person surrender to G*ds will, accept great personal or financial sacrifice for this role, live a life of service to all humanity. To get the job, a person goes through a long process to discern that they are truly called to this challenging life.
Other professions do not require this process (or they call it "grad school" or "internship"). However, I know that some folk use prayer and discernment to guide them in career choices, and some use their work (non-religious) as a way to serve humanity, feeling called to that role.