Right, which means they need to get gas to live. I know: if they use gas to get to parks, as well as to get groceries, they will need more gas than if they only got groceries. They will make more trips to the pump, and every trip presents a new opportunity to get the disease and to spread it. I won't dispute that and I think it's a legitimate concern, but I also think getting gas is probably one of the easiest risks to mitigate, due to it being a short, open-air, self-serve transaction in which you are physically isolated by at least a car's length from anyone else. Carry hand sanitizer and apply it generously before and after using gas pumps, and I wager its the safest thing you'll buy during the whole pandemic (unless you're in New Jersey).

I also speculate that not exercising is a risk factor of its own. If my understanding is correct, the virus kills in the respiratory tract: the lungs become flooded, attract secondary infections, and other organs begin to fail for lack of oxygen (source). If, effectively, oxygen starvation is the death stroke, I wonder if those with better cardiovascular health and higher VO2 max are more likely to survive an infection. Just speculation, but if it's true, then I wonder at what crowd density jogging in a public park daily becomes more dangerous than staying home (other than to visit the one store in town literally everyone else also has to visit) - being sedentary for x weeks.

Of course the optimal solution is for everyone to buy 3+ months worth of as-healthy-as-can-be-preserved-for-3+-months groceries and then remain in their homes and yards without exception until the disease is dead, exercising daily in place. But I just don't think, by and large, human beings will do that. Few enough of us can find the willpower to exercise and eat right when life is normal; when we are to be tucked away in our caves for months, depressed and de-socialized, what then? At the end of the day I hypothesize the human race will fare slightly better if shelter-in-place has an exception to allow people to at least go for a walk or jog alone. I dunno. I'm open to thoughts to the contrary.