I have tried several fitness trackers, and I believe that they are a great tool to be able to have an accurate log of your exercise efforts.
My first one was a little clip on (Fitbug Orb) tracker, and it did a good job of tracking my steps, but the battery would have to be changed every few months. Next, I got a Jawbone UP, and it was like a bracelet, and charged with a usb, and also tracked my sleep patterns.

That all changed when my daughter got a new Apple Watch and gave me her Series 2 Apple Watch .
I totally love it ! My exercise is swimming, and since it is waterproof, I can wear it when I am swimming, and it tells me how far I swim, how many laps I swim, and how many calories I burned when doing it.
It also monitors my heart rate , which is important when you are my age, and tracks my sleep, as well as sleeping heart rate.
It syncs with my Health App on the iPhone, so I have all of the information in one place.
I use the Carbmanager app to track all of my food intake, and the Apple Watch also syncs with that.

Last , but not least, I just love having the “Dick Tracy” phone on my wrist, and no longer have to dig around in my purse looking for the phone !