There are many fitness devices which can be used to track your health but now instead of buying a smart watch you can convert your regular watch into a fitness tracker using a smart buckle.
You can buy this device from Kickstarter and you can use it on any watch like Sieko ,Casio ,Rado ,Rolex etc.You can check the calories burnt , heartrate, count steps , distance and also track your sleep habits.This device is water and dust resistant,It is compatible with apple health and google fit.It is also very affordable since its just 39$.
SOURCE: Kickstarter , YouTube