Pritikin Recipes

I’m a 47 year old male. I’m 6’5" and 320lbs and haven’t excercised regularly for awhile. I recently started a martial arts class to try to get fit. The class does a lot of exercises like situps, knee bends, pushups, etc.

I’ve been going three times a week for about 7 weeks now. But the class is still making me huff and puff and be short of breath.

My question is: At my age, weight, and fitness level how long will it take before I start seeing improvements in my aerobic fitness level?