Enjoy a nice walk or run on this Hudson River front path. Total distance of ~10 miles out and back, but can be done however long or short you'd like! ~9 minute drive from hotel
If you're looking for something slightly more "challenging", check out this ~6 mile loop hike that gets you some elevated views of the Hudson River and Tappan Zee Bridge. Same starting point as the Nyack State Beach, ~9 min drive from hotel
Head down to Main Street to walk around. Grab some pizza (hint: Turiello's is the best) or check out some art at the Edward Hopper House