Some people seem naturally happy. They might work in coffee shops or grocery stores and at least give the semblance that their job doesn't give them stress. I recall working during summers between semesters and feeling much the same way with the strain of physical labor being the only tell tale side effect.My career has been fulfilling but also stressful and with increasing demands of clients who are less project experienced than ever, they come to us with demands which sometimes don't make sense. Thus my fatigue is about those demands plus the need for a change which doesn't revolve around meetings and deadlines. What is left for me now is the pleasure of dealing with colleagues some of whom have become friends and they appreciate the mentoring in a way I had not expected.
I suppose everything is relative and perhaps some of the people in those more physical jobs would have traded places with me. Who knows.