Obesity causes a decline in testosterone.
Lack of activity causes a decline in testosterone.
Both of the above cause a higher level of insulin resistence, worsening diabetes symptoms.
ED is the most overdiagnosed condition for men. However, if your man is fat, dropping 20lbs can do amazing things to his abilities. Further, healthy diet, proper sleep and exercise will improve the condition.
Virtually all men will do better in bed if they get 30-60minutes of cardio (real cardio) 4-5 times a week.
To increase testosterone and HDL (the good cholesterol), have your man lift weights and increase muscle mass. NO money for a gym or equipment? PUsh ups, dips using a countertop and a pull up bar work wonders.
Oh and if they smoke or use nicotene, if they quit they'll do much better in as little as 3 weeks (as well as raise their good cholesterol a few points).
If they are boozers they need to stop to be able to work better. Two drinks a day is still fine by most people's accounts. Just heavy drinking causes problems with standing at attention.
There is no excuse... get cracking men, or your women should be able to crack the whip on you.