Green leafy vegetables
Popeye was on to something. Although eating your greens won't result in bulging muscles (thankfully), it will turbo-charge your energy levels. Spinach and other green leafy vegetables such as kale contain nitrates, which boost the part of the cells that provide the body with energy. These are among the most nutrient-rich foods you can find, containing umpteen vitamins, minerals and antioxidants which reduce stress responses in the body - meaning you can put your energy to better use. Green leafy veggies are also rich in folate, which can reduce the risk of depression.