May the odds be ever in your favor. Imagine you’ve set the goal of running a marathon that’s 90 days away. You’ve hired a trainer who says this a less than optimal amount of time, but if you stick religiously to her fitness routine, nutrition plan, and sleep schedule, you’ll be ready come race day. Cheat in any of those three areas, she warns, and you won’t be able to run 26.2 miles on three month’s notice.