They started out tracking just heart rate and the number of steps taken. But these days, fitness trackers tell time, altitude, your location, how much you've slept, how well you've slept, and even help you pay for your ride on public transport.
But finding the right fit for your needs amid the mind-boggling array of choices can be tricky.
Jasmine Goh, 37, one of Singapore's top female marathoners, said: "It is important to choose a fitness tracker that is suitable for the kind of exercise you do, as well as the location you normally exercise in."
Here are some tips to consider when choosing a fitness tracker:
DON'T GET HIGH ON PRICE, DESIGN
Eugene Sng, 33, a fitness trainer with SG Fit Club, a club that conducts workout sessions at more than 20 locations around Singapore, said: "Neither the design nor the price means that it has the best function you need."
Some models to consider if you are..
Just starting out
For a person who wants to establish healthy lifestyle habits, generally walks briskly and runs outside only occasionally, and wants a simple solution that will motivate him or her.
Garmin's Vivosmart HR (left). Besides tracking your steps, sleep and calories burnt, there is also a Move bar feature which will urge you to get up and walk if you have been sitting down or inactive for too long.
Polar A360 also has a similar function.
Fitbit Charge 2 or Fitbit Blaze have a multi-sport mode to track specific exercises like yoga or running.
A casual jogger
For the casual jogger who just started to run for exercise, wants to keep in shape and loves to take part in running events. Completing a race is the main goal for this group, instead of improving on personal bests.
An entry-level wearable such as Garmin's Forerunner 35, which is user-friendly and tracks basics like calories burnt and steps taken. For those looking for a slick-looking tracker, the Fitbit Alta (left) is a sleek choice.
A serious runner
For a serious athlete who is willing to invest a lot of time, energy and money into becoming the best they can be. For instance, a runner who is training towards meeting a timing goal for a marathon or an active swimmer and cyclist.
Garmin's Forerunner 235 or Forerunner 735XT (left), the Fitbit Surge or Fitbit Flex 2. They are lightweight watches with a built-in GPS and heart-rate monitor - essential features for runners who want to track or plan their routes.
The main difference is that the 735XT caters to swimming, cycling and running. You cannot swim with the Fitbit Surge but the Fitbit Flex 2 is the company's first swim-proof wristband and automatically tracks your activities in the pool.
Instead, he said user friendliness should be a key consideration. He cited battery life as an example of ease of use, saying: "Owning a tracker that has long battery life is a must because it avoids the hassle of charging it frequently."
HAVE A SPECIFIC GOAL IN MIND
Before getting a tracker, one should have a specific fitness goal in mind, so that the tracker does not become a white elephant.
Sng said: "The key question to ask is, what is your purpose?
"People would be more willing to wear it if they have a goal in mind that needs to be tracked."
Henrik Olofsson, 32, head of fitness at TripleFit gym, suggested a guideline when it comes to determining what functions are really necessary.
He said: "If you run a lot, you need GPS and heart-rate monitoring.
"If you simply want to track your daily activity levels, you'd probably need one which only counts your steps.
"If you need proof that you aren't sleeping well, then a sleep tracker can be a validation.
"Ultimately, fitness trackers are very comprehensive today. You can track many metrics, but I would say my recommendations are step-tracking and heart-rate monitoring."
IT'S NOT THE BE-ALL AND END-ALL
While getting a tracker could motivate a person towards meeting a fitness goal, it is not realistic to rely entirely on a device to help one succeed. Ivan McCall, 32, the owner of Fitness Functions, said: "It boils down to how much mental strength you've got, to want to succeed in your goals."
LEARN TO USE IT
"The latest gadgets are good to have. They can motivate you but if you don't know how to use the information and data to help you meet your goals, then it defeats the purpose," added McCall.