Pack up your old kit bag, as the old song says, and set out on a hike. From Lewiston, try the Avery Hills around Avery Lake. Each hill and valley gives you new views of hardwood forests, wildflowers, berry bushes and wildlife. Another hiking area is north of Lewiston, called Rattlesnake Hills. (Don't worry, any real rattlesnakes are few, and will usually hide before you get close.) Take water, cell phone, a map and a bit of emergency supplies, just in case. There is plenty of public land in the area, so there's no need to trespass on private land.
For the experienced hiker, the High Country Pathway crosses the county. Michigan DNR offices have maps, and it is a trail through the Pigeon River State Forest, and through elk country to Clear Lake State Park.