It's perfectly fine to work out only on weekends and rest on weekdays

The gains of an intense workout session or two on the weekend are not dissipated if you don't have time to exercise during the week, researchers have found. — Christian Charisius/dpa

The slog of commutes, shopping, bringing kids to school and doing housework often leave scant time for exercise during a 35-40 hour working week.

Being ran off one’s feet at work, as the saying goes, often means little time or energy for real running, at least outside the weekend.