This is on point... You also give no actual numerical context. Are you saying you are working 40 hours a week and leave work exhausted? Are you saying you work 40 at work, and are on call/email/remote terminals for 40 more hours coordinating teams, putting out fires, designing architecture?
Even then, I would ask you to be more specific. I have a normal 40 hour a week uni job as a sysadmin, but it typically takes somewhat more or less (hey, sometimes I can get it done in 35, sometimes its 50 hours). However, for the last several years we have been so shorthanded, faculty wise, that I teach (at a minimum) two senior level computer science classes every semester (I was a professor at another uni). About mid semester, things will break, professors will make unreasonable demands of building out new systems/software/architecture, and I find myself doing (again at a minimum) 80 hours a week. On the other hand, I am not exhausted, as I enjoy teaching quite a bit, and I have been a sysadmin for many years and also enjoy that work.