Question about energy/stamina throughout the day?

I'm an aerobic instructor and have been involed in the fitness industry for many years, my cardio vascular fitness is really good, but if i or anyone else makes a sudden dash up some stairs or for a bus i'll be puffing as well. It's because you're using a different energy system when you need quick energy, you're using anaerobic and not aerobic. If you warm up over 5 or 8 minutes then you should be ok, if not then maybe you do need to look ar increasing your cardio workouts, but i'd say from what you've described that it's because you haven't warmed up properly.