The battle I fight almost every day is the battle between Night Me and Morning Me.
Take last night for example. I was out, playing poker, and Night Me says, "Woo hoo, it's fun to be out with my friends, pour another glass of wine." Morning Me says, "Just go easy. Don't stay out too late and don't drink to much, because we have an early meeting to go to and when the alarm clock goes off, I'll be sorry."
But Night Me doesn't care about the alarm clock the next day, because that is Morning Me's problem to deal with. And sure enough, Night Me wins the battle, drinks that little bit too much, and stays the extra hour. Then Morning Me wakes up the next day gasping for water, swiping for the alarm clock, and violently cursing Night Me.
Night Me doesn't care about going to the gym, or shopping for groceries, or ironing a shirt, or going to work. Night Me doesn't think about hangovers, or sleep deprivation. Those things are Morning Me's responsibility. Morning Me is the one who understands consequences, and who gets things done.
The battle is in the balance. It's a rare thing indeed to have Morning Me and Night Me satisfied at the same time, so I just work on balance. Each gets to win a battle every so often.