Free entrance over 10 miles of nature trails, and varied terrain make the Pelican Nature trail great for low cost fitness. The only cost is your gas to drive there.
Take Highway 99 from Fresno North for approximately 90 miles. Then take Exit 227 Kansas Avenue and turn left (west). The turn left on Carpenter, the second main street after the Kansas Avenue exit. Then turn right onto CA-132 Maze Blvd. which is approximately a mile from where you turned onto Carpenter. Continue for approximately 9 miles until yu reach the an Joaquin River National Wildlife Refuge on Dairy Road in Grayson.
Once you reach the refuge there are bathrooms, drinking fountains, and free hiking trail maps in structures at the parking lot. Please note that this is the only place with clean, well serviced, and relatively odor free restrooms within hiking distance. It is the only area within hiking distance with clean potable running water.
The San Joaquin River National Refuge boasts up and down trails with multiple options. If you want a more strenuous workout try the upper trail. As a bonus you are walking along a levy and have a beautiful view of the refuge. On the lower trail you are closer to the water and it is not uncommon to see a pair of beavers building a dam. It is also not uncommon to see U.S. Fish and Wildlife personnel taking apart the dam to keep it from flooding out trees in the vicinity. From my experience the staff is extremely helpful and willing to give you guidance on the best trails to take any given day.
If you bring a lunch there is an elevated viewing platform along Beckwith with benchs to sit and eat. From October-March you can often see huge numbers of Aluetian geese and a multiple of rabbits from the platform. Typically around January is the peak time for geese. During this time you often can not even see the ground in certain areas because they are nesting so densely.