I'm in week three of my commute, and I was able to really work hard almost the whole ride today. Only had to slow down a couple times. I can definitely feel the improvement in my legs...
I also really enjoy the shortcut I found through this little county park. I ride into the park through the back of a neighborhood, around a bike/jogging path, then down this long gravel fire-truck-only-road that leads out into the back of a different neighborhood. I'm the only one there in the morning (in the afternoon there are often some guys playing soccer in the grassy area). I saw a rabbit on Tuesday... and there are some really nice-smelling trees blooming in the park.
And best of all, it eliminates like 5 intersections from my route.
Makes me glad I bought a hybrid though, I don't think I could ride on the gravel very well with road bike tires.