When one stops to consider the resources required to perpetuate a life to a natural terminus, one realizes how futile the effort really is. Start crossing off life's necessities one a time, starting with the least requirement and figure out what you would have to stockpile (and how) in order to live out the rest of your days completely independent of the environment currently around you.

At 47, I would like to live at least another 20 years. What does twenty years of non-perishable food look like? How about twenty years of potable water? How about twenty years of breathable air? Basically, you are building a spacestation on earth. Assuming you don't regenerate/recycle any supplies, the volume for just one person is staggering.

2 lbs of food per day x 365 days x 20 years = 7 1/2 tons

2 gallons per day (one for consumption, one for application) x 365 days x 20 years = 14,600 gallons or 58 1/2 tons

2 liters of air per breath x 5,760 breaths a day x 365 days x 20 years = 8.5 megaliters