A spin around the park on a bike makes me feel good. One lap is about 6.13 miles. I've trained here for longer rides (including this London to Paris ride on a track bike that was 86 miles one day, rest on the second day, and 136 miles on the third day). I've sat there on a Sunday afternoon and have done as many as 10 laps (with rests in between). I switch in-between my carbon road bike and my steel track bike.
I live above TriBeCa and take walks into and around this area often. It's quiet, usually on the emptier side, and hosts a few gems of restaurants including Tiny's, Takahachi, and Odeon - all on the same block of West Broadway.
This place has one of the hottest rooms I've ever been in. The combination of barely being able to breathe from the heat to immediately jumping into a freezing murky pool is addictive. There's also a great roof patio for a change of scenery. A good old school New York spot.
Part of the Marlow restaurant group, Diner is one of the more casual / rustic options. The menu changes daily and is written out (most likely upside down by the wait staff) on your table or the back of a receipt. The only constant item is the burger, which to be honest, is one of the best in the neighborhood. If they have a breakfast sandwich for brunch, get that. The fried chicken sandwich (with dark meat) is also a favorite. They make scrambled egg dishes better than most. Dinner is solid all around (they crush a steak for two). Homemade ketchup and dijon mustard are on every table, so regardless of what you get, these two condiments are worth the visit.
I have old friends in San Francisco who grudgingly tell me that the High Line is everything that's wrong with New York. Well, too bad. To me, it embodies a culture that's constantly reinventing itself: a defunct elevated railway that was becoming a burden to the city ("we used to climb up there to throw garbage bags full of rotting Korean food at the Hasids!", noted a successful photographer's assistant) becoming a startling example of urban greening for the public good. The expert landscaping makes it feel like walking on a Montauk beach - but a stone's throw from some of New York's most progressive galleries and hotels.