For all fitness to be functional, it must be regular
Like, actually booked into the diary at the very minimum of twice weekly. This rule applies to everyone. If this isn't possible, my response to this is, some exercise is better than none. This won't have a measurable progressive or maintenance outcome.
Regular physical and mental stimulation will offer gentle increased cardiac (heart) and pulmonary (lung) function, decreased anxiety and depression. Lots of feelings of well-being and some lowering cholesterol and blood pressure too. It will certainly offer a mental break and a natural hormone boost. Not to mention the social factor which we all look forward to. Simply just having a laugh and enjoying the session for the sheer fun of it!