Aerobic exercise reduces the risk of many conditions, including obesity, heart disease, high blood pressure, type 2 diabetes, metabolic syndrome, stroke and certain types of cancer. Weight-bearing aerobic exercises, such as walking, help decrease the risk of osteoporosis.
It's the only answer thats a place with official jobs. A normal farm would be there too, but a backyard farm is someones hobby and not a paying occupation, so OSHA isn't in charge of that.