Always have a backup plan. Traffic jams, impromptu meetings, and alarm-clock failures happen (as does getting sucked into a rerun of The Real Housewives). We get it. Which is why it's so important to plan for contingencies. If you're too late to make it to your favorite kickboxing class, have a backup weight workout tucked into your bag. If your kid pukes in the middle of the night, make sure you have a few fitness DVDs at home. If you slept in and need to head straight to the office (or got stuck working late), plan a different time to hit the gym—as in actually write it in your calendar.