It doesn't take very much equipment to start running. You don't even need shoes, if the surfaces are not too harsh. You just have to do it. People, however, like to know things like their pace and distance to determine if they are improving. They also like to know their heart rate and other factors to know when they are pushing hard enough, or too hard. This is where the gadgets come in.
When I started running somewhat seriously back around 2006, all I had was an old Timex Ironman watch to use as a stopwatch. To figure out the distance of a route I ran, I used a website called G-Map Pedometer. With that info I could calculate average speed and pace with reasonable enough accuracy, but it took extra time.
Sometimes I would take my Garmin Legend GPSr with me, but that was awkward to use and carry. At the time there were wrist worn devices which used GPS signals to do all the tracking for you, but they were expensive. After deciding on the one I wanted, I watched the price drops and sales until it hit the point where I could afford one. What I got in August 2009 was the Garmin Forerunner 305 with a heart rate monitor. When I run, my heart can beat much faster than I like, so a constant reminder to slow down is important.
The 305 is bulkier than a watch, but easy to use. It tracks your route, speed, pace, elevation changes, and heart rate. It will let you know when you have hit certain milestones, and you can use it to setup things like Tempo training. Once back home, the data can be dumped to a program on your computer, or uploaded to the Garmin Connect site. There you will always have a record of your activities and progress.
I also used a website called dailymile. It is a place where you can share your workouts with friends and encourage each other, as well as track your activities. There are others like it, such as Buckeye Outdoors. They allow you to either sync your GPS device or enter the data manually. They are basically the same as Garmin Connect, plus a social aspect. Look for "PeterInMotion" to find me on those.
Then came the era of smart phones. During the autumn of 2011, I put aside my old Motorola Razr in favour of a Motorola Atrix. They may be called smart phones, but they really are fairly powerful little computers which just happen to have the ability to make phone calls and send texts. From the app store you can find a myriad of fitness programs. Many have free versions, with more features available for a fee.
I tried out several, and they were all pretty much the same. What I ended up using was Endomondo, just because Google had a sale on the Pro version at that time. With this installed on my Atrix, I only needed the 305 as as heart rate monitor, so I usually carried both. This came in handy when one or the other failed, and as a check. The days of the 305 were numbered, however. It was so much easier to just grab the phone, rather than strap on the big watch and wait several minutes for it to lock on to the satellites.
Since upgrading to a Samsung Galaxy S5 this autumn, I don't even need the 305 to monitor heart rate. The Garmin strap, being Ant+, syncs up with Endomondo on the S5. Now I have everything in the one device. The syncing with the website is automatic, so all I have to worry about is just getting out and doing something - and hitting the start button.
The Garmin Legend is now mounted to my bicycle for longer trips. It is tough and weatherproof enough to handle the job of displaying my speed, etc at a glance, so my phone can be tucked safely away for emergencies. The Garmin 305 still gets put to use once in a while too, when it is inconvenient to carry or access a big phone.
Fitness gadgets come and go, get re-purposed, and passed along to other people. Some lay in drawers or boxes gathering dust. Some are worn all day long, and some only as required. The important thing is that you stay active. If having something to play music and track your speed keeps you motivated, then great. Don't get a device, however, thinking that it will be the motivator. It is just a tool to help with your goals. You still need the drive within yourself to actually get out there and do it.