Answer:
Walked on a circular nature trail
Step-by-step explanation:
We are told that you walked 3 miles.
Now, we are also told that the reference point used to calculate the total distance that you walked was the same as the ending point.
For, one to end up at the same place where he started a journey using the same reference point, it means the journey was not a straight line but a circle because the radius would have to be constant for that to happen.
Thus, it means you walked on a circular nature trail.