If you think you're prepared, you're probably not. The most important survival tool is between your ears.
Do your homework... read, study, practice, learn.
^^ both great points!
It's not the time to find out if you can get a fire going when your near hypothermic and it's raining- you need to practice (a lot!)
reading how to build a debris shelter vs building one and sleeping the night it are two totally different things
carrying snare wire and never building a snare will likely insure you'll go hungry, same w/ a primitive fishing kit- again practice
survival skills are just that- skills, like any skills- they need to be honed
insure your practice sessions are safe- heading into the backcountry w/ meager equipment to practice is not a good idea!
the last bit I'd add is- the will to survive- this can't be overstated, there are numerous accounts of folks who had all the proper resources at their disposal, yet unexplainably perished- and as many accounts on the other extreme- folks totally unprepared, yet somehow survived. The mental aspect of survival doesn't get a lot of play, but it's importance is clear.