what makes people give their best .???

There are some people whom self-motivated with ambition behind their head. But some people get motivated by someone elses. They do their best not for nothing. but to achieve something. But some other people do their best so as they do not regret it later. If you failed in something just because you dont do your best, you will regret it more than fail after doing your best.

when the people is crazy about the work what they want then people give their best...

I think inner strength makes people best.I also believe that family,environment around people and education makes them give their best.