I've been going to fitness boot camp with a fellow producer and friend. It's something she signed up for through Brookline Adult Ed, and I just kind of tagged along. It's pretty tough going, so far. An eight-week program with 2 sessions per week, and we just got through the third session. I say "got through," because that's what it is, a test of endurance, stamina, and generally dealing the prospect of reaching one's physical limitations.
We do jumping jacks, "mountain climbers," "planks" (don't ask). We skip around the gym sometimes. We do sprints. We do TONS of lunges, so much so that it feels I may pop a quad. We jog in place. We use resistance bands. We do tons of ab and core work.
It's led by a personal trainer/field hockey coach type. She is great. We hate her. She makes us work. We love her. etc.
The whole thing is tremendous fun and hugely gratifying, and I love and dread every minute of it.