This one will be a long easy walk starting at Kensico damn down through Bronx River Parkway path to County Trail...and back. There is free parking there or metro north nearby (White Plains or Valhalla station are the best options) , contact me directly if you need help finding the Damn.
Out and back - No loops and mostly flat to enjoy the nature and take it relatively slow. Dogs are welcome on a leash , bring plenty of water and a snack if you like...sturdy sneakers are more than enough for this.
Bronx River Pathway: Kensico Dam to County Center Trail on AllTrails
https://www.alltrails.com/trail/us/new-york/bronx-river-pathway-kensico-dam-to-county-center-trail?sh=0fsgjo