NEW YORK (WABC) --Once upon a time you exercise, you sweat, you get tired, you cool down and you knew you had a good work out.
It was simple, but nowadays little computers keep track for you.
The little wrist devices track everything about your exercise and your movements.
It's your life on your wrist.
"There's my strength training. There's my jogging. There's my cycling. There's my running," said Rich Frankel, a tracker.
With his sophisticated fitness or activity tracker, Frankel is able to monitor all sorts of readings during his workouts.
"If I see my heart rate is elevated sometimes I'll check it, watching my heart rate when I'm working out," Frankel said.
With a number of different trackers to choose from, at various price points, it's your choice depending on what you want to know.
Malika Abdullah wants to buy one.
"I'm not someone that needs something like nagging me every second or this or that, just the important stuff," Abdullah said.
Dr. Jeffrey Borenstein heads the Brain and Behavior Research Foundation.
"I think these devices can help empower people to monitor their activities," said Dr. Jeffrey Borenstein, President and CEO.
Some track the number of recommended footsteps you take in a day to the number of miles.
Ever wonder how many steps you climb during a day and now many calories are you burning?
"It's kind of cool. Oh man, I'm putting up these amazing numbers and I would post them to social media. People would be like, what?" said Tommy Cooke, a dog walker.
Cooke will pound out double the steps than most people.
"It's estimating I slept six hours and thirty two minutes," said Dr. Steven Feinsilver, Sleep Center Director.
One interesting thing you can monitor is sleep.
How often do you get up? How restless are you?
Dr. Feinsilver is director of the sleep center at Mount Sinai Hospital.
"I'm not sure I'm convinced it's completely accurate, including using it myself, but it is close. And it's at least a place to start," Dr. Feinsilver said.
So go ahead, and follow your life on your wrist.
"Don't obsess over it. Monitor it. If you have a concern that's something that you can speak to your doctor about," Dr. Borenstein said.
It's up to you, how much you want to know.