If you are struggling with your resistance training program than you may not have your iPod pumped up loud enough.  Recent research shows that you can push much harder when you are lifting weights when you music is louder than when it is on softer.  Not only can you lift more but the same study showed that you can do more reps.  So whether your goals are muscle building or weight loss and muscle toning than pumping up your play list may get you there faster.

It seems that the extra loud muscle is received in the brain as a potential threat, and the result is an increase in released adrenaline.  This rush of the fight or flight chemical means more energy is deliver to the muscles allowing them to go longer than usual and lift more than usual.  The only down side is that this effect is only temporary so pump up your tunes for the last few exercises of your workout when you are starting to fatigue.