Can u exercise too much?

I know this is a fruity question but can u exercise too much? I do my gazelle 30 mins every day and I walk. I have been starting to run some, nothing major. I have thought about doing my gazelle for another 30 mins each evening. My inner thighs need toning up bad and I know it will take time to do this, would it help or hurt to add more time on the gazelle? Or would it not make a difference what so ever? Hugs Ange Open RNY 3/24/05 313/153 -160lbs