If you are looking to increase your workout efficiency in 2013, one of the best ways is through a heart-rate monitor.
Amazon has the Polar FT4 Heart Rate Monitor Watch (Black) for only $62.54 with FREE shipping. (But you can also get the cool pink one for $67.64 or bronze for $68.54.)
I wear one every single time I work out and it helps me to keep my heart rate in the “zone” plus it gives me an accurate calorie burn number vs the number from the machine at the gym (which can be inflated).
Or you can also check out Amazon’s Gold Box Deal of the Day is the Timex Men’s or Women’s Ironman Race Trainer Heart Rate Monitor Watch for $89.95 with FREE Super Saver Shipping.