While backup plans are never a bad idea, they consume a lot of time and are unrealistic to outline for every operation. I propose a blanket backup plan: be flexible. Accept in advance that things happen beyond your control. Be prepared and practiced enough to make alternate plans quickly. Those who can accept change, keep cool, and think on their feet stand a better chance at getting things done. Furthermore, an open mind radically reduces stress and can open doors to better possibilities outside the original plan.
Embrace flexibility. It may very well be the key to a more fruitful, healthier life.