If you visit Boulder, hiking is a central part of the experience. There are many trails that criss-cross Chautauqua Park, but if you hike the ones under NIST you will find them to be much less crowded.
Take the Table Mesa exit off the 36 Highway and head west (toward the mountains). Turn left on Lehigh and right on Bear Mountain Drive. You should see a trailhead on your right after you cross Wildwood.
To get to Chautauqua Park, take the Baseline Road exit off the 36 and head west until you see the park sign and road begins to curve up the mountain.