Timex Ironman Global Trainer Bodylink System A GPS and heartrate monitor built into a (large) watch
It is easy to understand that what you get out of a workout really depends on what you put into it. If you want to be fast, you’ve got to train fast. But an equally important and less intuitive aspect of training is the rest period. If you never give your body a chance to recuperate you end up training tired, which can lead to injury, demotivation, and subpar performance.
Training with a heart rate monitor keeps you honest on the hard days by not letting you slack off, and also lets you monitor your exertion to be sure you take adequate rest on the easy days. Timex combined a GPS receiver with a heart rate monitor to create the Global Trainer Bodylink System, and it is easily one of my favorite pieces of training gear. I have it mounted on my child-jogger and love to be able to see all my performance specs at a glance. Whether you run, swim, bike, or hike for fitness, this all-in-one training tool will give you more hard data on your performance than you thought possible.