Originally Posted by Lux Flyer

If he is able to maintain distance from other people while doing this, there is no issue with going out. The problem is being in close contact. You can go for a hike, run, etc, do plenty of semi-solitary outdoor things still and have a less chance of acquiring this than you would going to the grocery store where your risk of it being left on surfaces and ability to distance from other people is significantly impaired due to being in a confined space. This virus isn't just hanging out in the air where as soon as you step outside you're exposing yourself. It's transmitted through close contact. People SHOULD be going outside, getting regular exercise/fresh air because it does boost your immune system in addition to keeping yourself overall healthier while you're living a more sedentary lifestyle.