As a species we are hard-wired to adapt.  Those who can quickly adjust to a given situation or environment are most likely to survive.  This seems to be especially true when the situation is a group exercise class and the environment is the local gym.  Step into the studio, shut the door behind you, and watch as evolutionary biology kicks in.  Suddenly you are performing exercises you would never think of performing on the gym floor due to the simple fact that everyone else is too.  That burpee or box jump looks much more appealing when instead of sticking out like a sore thumb for doing it you would look out of place by refusing .  Fear of hyperventilating lessens when you glance across the room and see a sweet elderly man happily completing his second round of mountain climbers.  Exercising becomes fun when you have someone to commiserate with, make faces at the teacher with, and go out for a non fat soy latte with afterwards.  Nothing builds friendship faster than tandem hardship, even if that hardship is a heavily loaded squat.  Going through the trenches together helps people bond like nothing else.  Before you know it 45 minutes have gone by, you’re sweating more than you ever would be if you worked out alone, and you’ve made a few new friends.  Maybe there is something to this group exercise thing.