How often is this really true anymore? How often does your life actually depend on a decision you make or an action you take? I'm not talking about not eating a donut because 20 years from now you might have a heart attack, I'm talking about immediate consequences of your actions. Is someone going to die if I make the wrong decision here or if I don't work hard enough today? I'm not talking about financial ruin or becoming homeless, I'm talking about the immediate end of your life.
Most of the examples I can think of don't hold up to analysis. Ironically it's the simpler more mundane decisions that have the potential to be catastrophic (should I change lanes now? Should I take the elevator?). In truth, in the U.S our very lives no longer depend on our everyday decisions.
If you choose not to work and earn a living there are charities and government programs that will provide you with a place to sleep and several nutritious meals every day. Provided you have the will to live and a basic sense of self preservation your life no longer depends on how hard you work.
I tried to find other examples of things we might do "as though our lives depended on it". Running from a burning building? Fighting off an attacker? These incidents are so rare most people aren't affected by them their entire lives.
Again, the examples I could find that meet the criteria are mundane decisions and actions. Hardly the types of things people would say they are doing "as though their lives depend on it".