There are many ways to find your easy pace, but one of the most accurate is to go by your heart rate!
Your Easy heart rate should be below 75% of your Maximum Heart Rate. A common calculation for finding your Max HR is 211-(Age*.64), and you can see in the table what your Max HR is and your Easy HR threshold is based on your age!
Easy running is what builds up your endurance and aerobic. It is the foundation for you being a fitter, stronger, FASTER runner! For newer runners, almost all (if not all) of your runs should be at an easy pace. For more experienced runners, you should aim to run easy for the majority of your weekly runs. If you "run hard" every day, you're doing more damage than good, putting yourself at higher risk of injury, plateau, and burnout!
The most important thing to remember that an easy run can change in pace depending on the day: the weather and how you feel on any given day can have a big impact. You might find yourself running at very different paces from one day to the next to keep your heart rate in the right zone. This is normal!
Keep your heart rate in the Easy range for the majority of your runs, and you will see big improvements in your endurance, stamina, and aerobic conditioning. In fact, the biggest sign of progress is when your easy pace gets faster when you're running in your easy heart rate zone!
GEAR TO HELP YOU
In order to track your heart rate during activity, you'll need a heart rate detecting wearable. Most people wear a smartwatch, like an Apple Watch, Fitbit, or a Garmin (which comes in a range of prices and models, from the ultra-affordable Forerunner 35, to the wildly popular Forerunner 235 and Forerunner 245 with Music, to the ultra-fancy Fenix Series). These watches will give you your pace in real-time, and also measure distance, heart rate, elevation gain, and more! You can also get a heart rate monitor strap that pairs with your run-tracking app on your phone, like the Polar H10 or the Wahoo TICKR.