Once one starts drinking port it is rather hard to stop...... 
Exactly and shit does it cause hangovers if you drink a whole bottle

Which is why about 30 years ago I decided I had to not drink it unless we had guests. But work kept giving me a bottle of Taylors every year and some were 10 years before opening. Must still have some but either it doesn't keep in the bottle or off the shelf Cockburns is better