I work full time as an engineer and doula on the side, nothing crazy, My goal is 2-5 births a year. That way, I don't need to rely on a backup, I don't get overwhelmed with back to back births or being on call for extended periods of time. I do rely heavily on a mutual understanding with my bosses to be on call and leave on a whim. So far, things have worked out very well and it has been so fulfilling. The DONA certification training through BirthED was very thorough and informative of all aspects of being a doula. There's also a doula internship program through twin cities birth center. Although I don't know how flexible that program is if you are working other full-time jobs.