The energy needed to raise the temperature of 1 kilogram of water through 1 °C, equal to one thousand small calories and often used to measure the energy value of foods
They could go for a hike or a walk. Hikes in a nearby forest are a great way to see nature on a daily basis and free of cost. If in an non rural area, such as a city, walking around town is a great way to get more physical activity! Another great way is to visit a zoo; most zoo have walking distance between the different animals. You can get both the active and nature in that as well.
(And I can't think of another one sorry)
