When you’re three weeks out from race day, your training plan will most likely instruct you to start tapering. The taper is critical to success on race day. Think of it as your reward for all of those weeks of hard work. But ironically, many people feel like they have to run more than their plans specify during these final weeks because they’re feeling so good, and they think more is better.

Remember that it’s almost impossible to undertrain for a marathon, yet it’s easy to overtrain. And if you overtrain, you’ll end up wiped out and sluggish on race day. Generally, your training plan will have you run about 75 percent of your typical mileage three weeks out, then 50 percent two weeks out, then 25 percent during race week. No matter how energetic you feel, don’t cheat and add miles back in because you’re feeling good.