The fittest people on the planet once struggled with their first push-up. No one is born in pristine physical condition; they’ve committed to getting themselves there. If you’ve decided to take the plunge and make this year your fittest yet, congratulations! As you’ll see, getting started is, quite literally, half the battle.  But once you’ve started, you have to stick to it. You may be riding a resolution high at the moment, but how do you fuel that fire for the rest of the year — or the rest of your life? You need actionable, evidence-based tips to fall back on.  Credit: Victor Moussa / Shutterstock Here are six tips…