You are so right, being in shape is one of the best preps to have. I know preppers who have all the food and other essentials but they cannot walk more then a few miles without getting sore legs, feet etc. and this is not even with carrying a backpack....
Many people who have the idea that they can simply "bugout" across town or province/state/country by foot once they abandon their car in the traffic jams are in for a rude awakening. Can they really walk 15-20 miles on a paved street / road or worse on un-developed land. Many could probably do it the first day, but what about the 2nd, 3rd or 10th day and longer if needed?
The same goes for biking. Can they really ride a fully loaded bike for 25, 50 or 100 miles a day? By the end of day one (if they make it that far) their legs and butt will be so sore that the next days travel is not going to be pretty...
Next time you see person touring on a bike, ask them how easy it really is and the common problems they face.
My current fitness is a combination of walking to and from work (9 miles) minimum 2 days a week carrying a my laptop, lunch etc in a backpack. I do this in a all types of conditions: rain, snow or sun.
On the other days, I bike the almost the same route and it is actually harder then walking as it is uphill both ways. (just like your parents told you about their routes to school!!) There is one steep hill that whoever designed it must of been a sadist and had never rode a bike in his life.
On weekends, it is not unusual to go for a 4-6 mile walk carrying our BOB's for weight, through a local park that is on the edge of a steep ravine. Other weekends a 25-30 mile bike ride is normal.
Dental and medical are up to date. Twice yearly dental and once per year physical exams are the minimum for us.
Weight wise...well we could all stand to loose a few pounds...