agreed, you have to take the whole picture into account, diet, overall activity, etc. I've got a desk job and I try to get cardio workouts in 4-5 times a week.
Qigong, by itself is insufficient for healthy people. Healthy meaning no external presentation of illness. Better to do cardio (I have found) on its own days and qigong on the other days.
I do not do physical labor so I need to supplement with some type of cardio workout. Funny thing is that people who do physical labor do not gravitate towards qigong! I wonder why?