It always helps to be in good physical condition, and I have found that moderate strength and cardiovascular training has improved my kiting and my level of comfort on long distance kite trips considerably. I would consider the following rough equivalents

Trip difficulty Time on the water Equivalent jogging Equivalent cycling
Easy 1 hour ½ hour 1 hour
Beginner 2 hours 1 hour 2 hours
Intermediate 3 hours 1 ½ hours 3 hours
Difficult 4-5 hours 2+ hours (half marathon) 4+ hours
“Golden” 5+ hours 3+ hours (marathon) 5+ hours