I am a big believer of Boot Camp style classes and I am MUCH more motivated working out in a park on a beautiful late summer afternoon than I am trekking to a stuffy gym to pay big bucks for a personal training session. I have been extremely impressed so far with the outdoor circuit class outside on Saturday mornings at 9am held in John Jay Park at 77th between York Ave and the FDR. The class size is small — so you feel like you get tons of attention/instruction AND you can’t hide(i.e., in my case, I work out much harder). There is a ton of equipment too, so there are always plenty of options for working all the different muscle groups. I also like having the flexibility of picking which classes I want to go to, as opposed to buying a 3-week package and forfeiting the classes I can’t make. The outdoor classes are offered several weekday evenings and on Saturday mornings, but I have only been to Saturday mornings so far.