We've all been there: Your alarm wakes you with a jolt, reminding you that you planned to hit that 6 a.m. spin class. Except dinner with friends went a little late last night, and you are so. Incredibly. Tired. But if you skip your morning workout, you won't…

You can't learn a new skill without a bit of practice, right? But even if you practice every day, you may not be getting the most out of your practicing. Repeating the thing over and over again is one way to do it. Or you can try another method that scientists…