I personally like running outside way better because you get to see the scenery, you're outside enjoying the weather, and when you're on a treadmill you're in a gym, running in one spot is boring, there's nothing to look at, and I feel like when you're running you can actually see the end of your destination so it helps you to push harder and follow through versus on a treadmill you're staring down at the numbers and just counting down every single second until you're done. So I feel like running outside is definitely more enjoyable.