We made a good point here recently. The reason people go to the gym or go to classes or to a trainer for an hour 6 or 7 days/week is to try to compress a full-day's worth of physical activity into a manageable amount of time.
Thus we raise the intensity. Instead of lifting light rocks from the field all day, we do 4 sets of heavy deadlifts, and done. Instead of jogging for one or two hours, we do 30-45-second sprints.
Furthermore, a good balanced program can pack that in with minimal or no risk of injury, unlike somebody who shovel-digs ditches all day. The thing is, in the western world very few jobs require day-long heavy lifting any more. That is all mechanized.
Today, even professional tennis players (and all athletes) do their gym programs in addition to their sport training. Playing a sport is more of a use of fitness rather than a cause of fitness. Even many people who do a lot of work with their bodies (eg carpenters) go to the gym to stay fit for their work.
As readers know from endless repetition, we recommend, for general fitness for life for men and women, a balanced program of resistance training (heavy weights), calisthenics, and cardio (meaning heart rate elevated well-above comfort). We also recommend nutrition approaches to meet your fitness goals.
