Good Morning;
I have been running and training for nearly 40 years. For most of
that time I never used a watch and have never used a heart monitor.
Neither are essential to the process. They do add useful data that
will help you see where you are in your progress but you can get a
better idea from racing.
One race a month will show you exactly what you can do, how far you
have come and how close to your goal you are.
Last year I participated in a study of "senior" runners that gather
lots for data before, during and after each run. At first I tried to
keep up with the information myself. After a while I stopped and just
check the information after each run. I learned a lot from the data
but none of the new information made my performance any better.
Now that I have said that, a GPS watch (Garmin especially) is a good
investment. They are well made, reliable and provide excellent
information. But they are pricey. One alternative is to buy a used
one from eBay. The 100 series is about $40. That is not a break the
bank investment and if you discover you don't really need or like
wearing one, you won't feel ripped off.
Heart monitors are a different story. I assume you have seen a Doctor
and been cleared for running. Target heart rate training is a trend
that waxes and wanes. Those that like it, love it. Others don't. I
find it a distraction. Part of the joy of running in being in the
moment. Purging my brain of all the worries of the day and feeling my
body work. The more data I try to track while I run, the less I enjoy
the run.
So in sum. If you think a watch/monitor is for you go for it. Go cheap
at first and see if it helps. Then upgrade or discard as you discover
how they work for you.
Keith