The most important thing that human need is in the level of physiological need relates on so many activities done by human being such as eating, sleeping, and drinking, make love, etc. In short, the need is to have physical health.
However, with so many things offer by the modern world, it seems like we abandon this need with our desire to waste our money in the junk foods. Moreover we also have too much focus on working without providing some spare time to have regular exercise.
Generally, when we pay attention on what we are eating, we already do the first requirement of getting healthy. However, to keep our fitness so that we will not be easily get ill, the antibody need stimulation that can be achieved only if we move our muscle and produce some sweat.
You do not have to do heavy lifting or running for 20 miles a day to be healthy. The most important thing is that you do it regularly. Varieties are also needed to avoid being bored on the very same exercise each time you have spare time. Meanwhile, in what you eat you must consider having healthy diet containing enough quantity in macronutrients (such as protein, fat, and carbohydrate), minerals, vitamins, and fiber.