A relatively healthy body is needed to create hardness. So the healthier you are the stronger and longer lasting will be you erections. If your health is not so good, this will be reflected in your penis hardness and how long it stays hard.
The level of hardness can vary, so if you get hard but not as hard as you would like, then it’s an indication that you need to improve your health. If you get some hardness, but it does not stay hard for very long then again, you need to look at living a healthy lifestyle.
Diet is where you need to start. Being overweight or obese has a direct relationship on how hard you get. You will have to lose some weight, if you are overweight. Being overweight is related to a variety of illnesses that can plague you, if you maintain that weight or increase that weight.
All of these suggestions and steps are designed to improve your cardiovascular system, blood circulation, increase nitric oxide, lose weight, and increase mental attitude.