Thomas Jefferson was probably the first American to use a pedometer. The new generations of fitness trackers that have followed that first mechanical instrument are far more sophisticated.
In addition to counting steps, they can monitor heart rates, track sleep and count calories. Some can send and receive data from a smart phone or a computer. Others will help you keep track of calories so you can monitor how well you are following through on your healthy eating plans.
These devices can connect people and encourage competition between friends and family members in maintaining a desirable level of activity. It might be just what some of us need to remind us of our resolution to take at least 10,000 steps a day during 2015.
Gizmodo did an evaluation of fitness trackers that might help you select the best one for your own needs. The Consumer Reports evaluation is dated, but objective as always. And Dr. John La Puma has done an evaluation of exercise machines for 2015, not just fitness trackers, that should be very helpful in following through on healthy habits.