Do what your parents would do if you were staying up late at night to play video games every day - Set yourself a bedtime.
I usually set my own bedtime to around 11 PM, but I give myself a space of 30 minutes after in case I need to finish something in a game I'm playing. This is usually plenty of time to reach a save point or otherwise end the game.
It also helps to make other routines for yourself during the day. Set an alarm clock to wake yourself up at a regular hour every morning, to help enforce your sleep schedule. Follow it, even during weekends, so that you don't ruin your carefully-laid-out schedule just because "it's the weekend". Make another activity party of yoru daily life. For me, it's work, but for you, it could be a morning jog, or reading a chapter from a book, or even an exercise routine if you're feeling like you REALLY want to get healthy.
Most important is finding something to do outside of your gaming. But it also definitley helps to find someone to do it with. Gaming can be a social activity, but so can anything else if you do it right. Jog with someone, get a morning coffee at a local coffee shop, or just talk with someone about your plans for the day each morning.