Children are far more delicate than adults, since they lack our fireproof skin and utter unafraidedness of a giant gorilla perched on top of the Empire State Building. Let children flourish on gentle grounds with today's Groupon for children's fitness packages at My Gym Children's Fitness Center on West 66th Street. Choose between two options:

• For $45, you get a lifetime membership, two classes, and unlimited play (a $120 value).
• For $249, you get a 90-minute child's birthday party (a $650 value).

My Gym Children's Fitness Center, which currently has more than 200 international locations, began more than 25 years ago as a structured place for children to safely play, acquire new skills, and romp off a sugar buzz. All classes are organized according to age level (starting as young as 6 months) and designed to incorporate the latest physiological, psychological, and meteorological research. My Gym offers classes for all developmental degrees, from Tiny Tykes, a class for parents and babies that focuses on movement, to Champions, designed for kids up to 6 years old to master sports and gymnastics skills. Schedules and class options vary; click here for the class schedule. My Gym's energetic instructors are experts at using music, dance, and gymnastics to build youngsters' strength and self-esteem while simultaneously stimulating their giggleplexes.

Alternately, the My Gym birthday party gathers up to 15 wee ones and four imaginary friends to enjoy age-appropriate games and activities. Bustling bambini enjoy exclusive access to the entire facility, allowing kids to run wild with rides, songs, puppets, Space Flight, and more, all supervised by experienced My Gym staff members.