The Timex Marathon is a battery-powered digital watch with a light that illuminates its face. Besides displaying the time, the Marathon has a timer, stopwatch, alarm and pulse mode to calculate heart rate. You can set the watch to display in 24-hour military format or in 12-hour a.m./p.m. mode. You must reset your watch after replacing the battery.

Press and hold the "Set/Clear" button on the bottom right of the Timex Marathon. A message will appear reminding you to hold the button for two seconds.

Press the “Start/Stop” button at the top of the watch to advance the hour until it reaches to the correct time.

Press the “Mode” button at the bottom of the watch to adjust the minutes. Press the “Start/Stop” button to advance to the correct time. Set the date in the same way.

Press the “Set/Clear” button to save your changes.