I've discovered this exact same thing after moving from the (albeit small) city and into the countryside. Before, I was obsessed with speed and felt I'd failed at the run if I ran slower than I had run before.

Now I run on trails so my pace is naturally slower but I have so much more fun! I meet all sorts of wildlife, stop to say hi to squirrels, admire views and take in my surroundings. I love how the terrain brings me into the present moment and I always feel utterly renewed when I get home, not matter how fast, slow, muddy or tired I got.