First of all, you need to figure out who your insurance is through. BlueCross of Illinois is not related to BlueCross of NJ. If your employer is based out of Illinois, then you have BC of IL and can use the NJ network, but the plan (from IL) otherwise has nothing to do with them (in NJ).
Or, if you want to skip the semantics, just pull out your card and look at it. And then, you can call the number on the card to SEE if they have any programs and how they work.
Normally, you cannot just go to any gym and you NEVER can use your FSA. However, some plans have discounts for gyms. And in some cases, like United Healthcare, if you GO to the gym X number of times per month, then they'll actually reimburse a fixed amount. But, it has to be tied into a network that they can track. When you scan your card at the gym UHC is actually notified. They don't know if you actually get on the tread mill or sit in the cafe drinking soda, but it's the best they can do.
Moral of the story....call and ask.
Some health insurance plans do offer discounts on gym memberships, but not all. Contact your health insurance company or licensed agent to find out if this is covered by your plan. You may also want to ask your employer’s HR department about discounts.
Generally speaking, you cannot use FSA funds to pay for a gym membership. However, if you are diagnosed with a specific condition and your doctor prescribes a treatment regimen that includes gym-related activities, a portion of your gym costs may qualify for payment from your FSA.