Home › Top 4 Fitness and Gym in Hackettstown, New Jersey Find best Fitness and Gym in Hackettstown, New Jersey, with all necessary contact information, including addresses, phone numbers, working hours, map locations, and website links. Riverside Health & Fitness Center US, Hackettstown, NJ 078401892 NJ-57 Retro Fitness - Hackettstown (NJ 07840) US, Hackettstown, NJ 078407 Naughright Rd Riverside Kids Gym US, Hackettstown, NJ 078401892 NJ-57 Planet Fitness - Hackettstown (NJ 07840) US, Hackettstown, NJ 078401965 NJ-57 #13-2