If you don't drink enough water, you will feel tired.
If children eat a lot of sweets, they will have problems with their teeth.
If you don't sleep eight hours every night, you will feel moody.
If we eat chocolate, we will feel happy.
If we don't eat fruits and vegetables, we will have health problems.

If my parents worked late, I would give them bread and cheese. (This implies they don't usually work late.)
If we made noise in class, we would stand at the front. (This implies they don't usually make noise.)
If I felt sad, I would talk to my friends. (This implies it's not the case now.)
If I didn't know the answer to a question, I would try to find the answer when working in a group. (This implies I know the answer now, or the question isn't being asked now.)
If I felt tired, I would take a shower. (This implies I don't feel tired now.)