The realization that you have been living wrong.
The realization that you need to change your ways before you fall deeper into the hole you've dug yourself in and die.
You've had enough of the shitty and miserable conditions you live in and suddenly get the instinct to get better. To persist. To survive.
You might be afraid and anxious of change, but you know that it's the only way out of this situation. The alternative is stagnating and dying where you are.
Start small. Clean your room a little. Walk around a little every now and then. If you make too many changes you'll get overwhelmed. So just take it day by day. Those small steps will build up into a productive habit that will be as natural as breathing.

Something like that. I dunno.