The Greenbrier River Trail follows a former railway line for 78 miles through the valley north of Lewisburg. The nearest access is around Caldwell, a short drive east of town, where you can take a flat walk or bike ride beside the river.
You do not need to tackle the whole trail. A short out-and-back gives you the river, the old rail grade, and a calmer view of the valley than the downtown streets can provide.