I thought the original shot (while taken a cloudy day) was decent until I dropped into LightZone and made a few clicks of the mouse to create the tweaked version.
The LightZone “Relight” tool made an immediate improvement with just a single click. I went a little further though, and isolated the handful of leaves in the photo as a region to add some color saturation. Then, finally, I sharpened the photo just a little to bring out some more local contrast in the details. Total editing time was about 5 minutes.