Add Yahoo as a preferred source to see more of our stories on Google. As you head into the gym, you likely already have a workout plan in mind. Maybe you're taking a light jog on the treadmill, or you ...

(CNN) — As you head into the gym, you likely already have a workout plan in mind. Maybe you’re taking a light jog on the treadmill, or you’re working on some bicep curls on arm’s day. To get the most ...