Suddenly everyone we know is obsessed with hottie trainer Mark Fisher, renowned for his intense workouts, wicked sense of humor and high-profile clientele. ("I wanna work out next to Patti LuPone!" one particular friend moaned.) We haven't gotten as far as registering with Mark Fisher Fitness (MFF) but we have watched almost all of his YouTube clips, and we definitely feel it in our core. (All that laughing undoubtedly helped tighten our abs.)

Below, Mark revisits one of the basics of any good workout (and the source of one of the most annoying memes of 2010): The plank. You might think you've mastered it, but proper positioning is everything. As Fisher reminds us, "mean old Mr. Gravity is gonna wanna turn you into a slutty porn star whore!"