If you've been feeling a little stressed-out lately, it might be due to an iron deficiency: pumping iron, according to a recent study, may be the answer to diffusing anxiety.

Researchers at the University of Florida's College of Health and Human Performance examined the anxiety-reducing effects of weight training at moderate (half of maximum ability) and high (80 percent of max) intensity levels. Test subjects who used the low weight loads to perform a high number of repetitions experienced a "significant reduction in state anxiety" within two to three hours after their workout.

"There are theories that lifting distracts you from worries or provides a sense of mastery," says lead researcher Brian Focht. So why did the group that lifted heavier weights derive no such benefit? "It may be due to the fact that some people find intense exercises unpleasant."

The point is, says Focht, "we've learned there are psychological benefits to resistance exercise, and you can get them without expending a lot of energy." Pass the dumbbells.