I couldn't find my GPS watch and was trying not to freak out. My entire family pitched in to get me the watch a few years ago.
They bought it for me because it has a built-in heart rate monitor. The heart rate monitor chest strap I was using before left a bad impression on me. By that, I mean it was cutting in to my skin and leaving scars.
I never felt it when running. The second I took it off though... Ouch.
The great news is I found my watch in the dark unknown crevices of a couch.
Now, you don't need a fancy GPS watch to run. I used a phone app (Runkeeper) for the first year I ran. Unfortunately, as I'm slow, using GPS on the phone killed my battery before I finished my first half-marathon. Because of that, I started to look at GPS watches.
But that's just my geeky need for information. At runs, there are mile markers to tell you where you are. Your phone or regular watch can tell you how much time has passed.
In my calorie-counting days, I wanted a count of calories burned. I also like to check my pace and heart rate. But, unless you have a medical reason to watch your heart rate, don't let not having a GPS watch stop you from running.
The benefits of running or walking don't magically improve just because you strap on a watch.
Former high school water girl (really) finally running.