If you are interested in long walks in nature, the West side of Hillsborough county has a bunch of options for you. The main thing that you need to know is that this is Florida, it is a giant swamp filled with mosquitoes and fire ants, so you need to prepare accordingly. Lake Rogers Park is a good place to start but there are a ton of other options. I suggest visiting the Hillsborough County Park website to find a location that works for you. Pay special attention to the parking instructions as they are usually lousy.