It's Friday so the pressure is going to be on today to meet your mates at the pub, have a few laughs, and have a few pints.
Tell them you'll meet them, but you have to do something else first. Then go and do your workout. When you get to the pub, order your pint and a glass of water. Drink the water first, to quench your thirst, then enjoy your pint. Then another glass of water. If you stay hydrated with water you won't drink as many pints.
Give it a try. You'll also through straighter darts.