Nobody really wants to fall in the "sedentary life style" category, do they? It's like flunking Gym Class. Losers, right?
Sedentary is generally defined as less than 5-7 hours of strenuous physical activity per week. That's a low bar, since many or most adults that I know seem to have a sport they play either seasonally or year-round at least once weekly.
What is "strenuous" naturally depends on the level of fitness, so it is easier to define what is not a strenuous hour, like walking. Basketball is strenuous, Baseball and golf are not. Heavy sweat is one measure of "strenuous", as is heart rate or deadlift weight. For example, many "cardio" exercises can be done strenuously or non-strenuously. Swimming, running, biking/spinning, and rowing can be done one of three ways: semi-comfortably, energetically, and full-out anaerobic sprints. The only way to make them "strenuous" is to do them for time x distance so you can compete with yourself.
When it comes to weights and calisthenics, "strenuous" is fairly obvious: if you can't do any more weight reps or pushups or jumping jacks, and your sweat is dripping on the floor, it was strenuous. "Strenuous" implies "strain," ie going beyond comfort to serious mental and physical effort despite discomfort and stress.
The CDC offers two levels of recommendations for adults, one for "Benefit" and one for "More Benefit". Their "More Benefit" recommendations turn out to be very similar to the sorts of programs discussed on our website: combinations of weights, HIIT cardio + endurance cardio, and calisthenics. Many people are rightly distrustful of government advice, but since it happens to roughly correspond to ours it might give their experts some credibility.
(They have separate recommendations for older than 65-70, but I see no reason for that. There is no necessary or observable correlation between age and fitness in adults).
