Yoga
Being stuck indoors has really opened my eyes to the importance of being able to get a good cardio workout at home.
I can imagine many scenarios where keeping up your cardio in a confined space would be important in a shtf situation.
In a pandemic situation worse than covid-19 (say Ebola), you might be required to stay isolated in your home for months on end. However looting or civil unrest might require instant mobilization.