We've seen this group working out so many times, every time we've ever been in Park Circle around 10 a.m. on a Saturday, and they always look like they're burning tons of calories with all those lunges, interval laps, and sit-ups. Plus it looks like it could possibly be fun. Bonus: it's free. So why haven't we tried it yet? Don't be like us, get out there next Saturday and get your workout on.