Can’t figure out why you’re always dragging? Lack of iron may be the blame. According to a new study, fatigued women reported feeling 50% less tired when they took iron supplements for 12 weeks. Participants took 80mg each day, which is more than the RDA of 18mg contained in many multivitamins. However, don’t self-treat with larger doses without talking to your doctor first, as too much iron can be dangerous. And keep in mind that a pill isn’t the only answer: beef, seafood, and poultry are also great sources of iron.