Live a healthy lifestyle.
Exercise regularly, a have a balanced diet, maintain a good weight in ratio with your height. Being too overweight and obese can cause Diabetis then your grounded. The medical is thorough, BP, ECG circulation, lung function, hearing, sight, blood & urine. They poke your stomach aswell dont know what theyre looking for there?
Drink in moderation cut smoking out as this will reduce circulation and lung function.
Thing is you can do the above but the pilots I fly with dont seem to worry. They drink lots and are overweight. So I wouldnt worry too much you could go out and get knocked down tomorrow.....