What motivates you to do your best work?

[ahnuld]

I recently did some project type thing that was the hardest thing i've ever done in my life based on amount of work in a short period (like 4 days 16 hours a day of tough mental work). Normally, for exams and things like that, ill make up excuses for myself at say 10 pm and quit working when I probably should continue. However for this thing I just kept going becuase it needed to be better and I was running out of time.

So now that I finished it and I can reflect, I think the main motivation factor was a fear of public failure (making a fool of myslef). This doesnt happen with exams as its a more private failure, and with poker its basically the same thing and there are very few motivators to keep playing besides just general competitiveness. So im asking what is your biggest motivator that will make you work like you didn't think possible. Love? Your children's well-being? Pride? Fear of failure?