There are three loop trails, each about 3 miles. They're located in the Lake Talquin State Forest and are all part of the Florida Trailwalker Program. Each one has a portion of the trail which follows the lake. There's plenty of overhead canopy for shade.
Take Interstate 10 to Hwy. 90 W (exit 27), go E 2 miles, turn S at Geddie Rd. (CR 1585), go 2 miles, turn W on Hwy. 20, go 5.5 miles, trailhead is on the N side.
http://www.tripleblaze.com/trail.php?c=3&i=7643