I recetnly ended a project needing constant overwork for about 43 days and for the last 15 days I didn't really want to get up from bed. But every time, I just repeated "I love him I love him I love him" and reminded myself of one thing. And that made me jump out of the bed.
And what's that?
For me, my biggest motivation is my (yet nonexistent) child. I want him (and yes, I do prefer a "penis kid") to grow up without any troubles and have enough money to start a business of his own as soon as he becomes an adult. Also love and live the way he wants.
He'd just need to study and go after what he likes and boom, he'll have enough to fund his startup and make his dream a reality.