Ever walked into the gym, made a beeline for the rowing machines (maybe all the treadmills were taken?), plonked yourself down and then kind of... not really been sure what to do next? We hear ya! But ...

Fun fact: When working out on a rowing machine, you engage up to 86 percent of your muscles at once. Basically, it works your whole body, and really well—which is probably why the number of people ...