FITNESS ALFRESCO

Think outside the gym! Your guide to budget-friendly, open-air workouts in all five boroughs

A T Shariff Harris’ Tuesday-night boot camp in Central Park, the sounds of a nearby bagpiper underscore the unpredictable nature of exercising in an open, public space.

The spontaneous “Braveheart” moment and other delightful surprises like it are why class members like Lou Amato love coming to Harris’ boot camp after work. “It’s a good way to mix it up, instead of doing the same things at the gym,” says Amato, 28, who works in finance.

Harris, who started these classes in April, is one of countless New York City trainers leading outdoor fitness classes that are much cheaper than the popular boutique workouts that cost upward of $35 a pop.

Such workouts don’t offer showers or fancy grooming products, but they do provide some much-needed fresh air and a killer workout — at a fraction of the price.

“It’s a good way to get personal attention from a certified trainer without paying for one-on-one time,” says Stacy Berman, who’s taught a Central Park workout since 1999.

The city’s Parks Department, which has its own lineup of outdoor workouts, has a few rules for park fitness entrepreneurs: No ads are allowed on the premises, no money can be exchanged for services while on park property, permits are required for groups larger than 20, and fitness equipment has to be light enough to be carried in and out, and cannot be tethered to any park property.

At $10 per 45-minute class, Harris’ may be one of the best deals in the boroughs, but his isn’t the only affordable option for getting sweaty outside.