Subject: How can the equation for work (W=Fx) be proven?

I've been having trouble seeing why work is defined by the DISTANCE 
something is moved against a force. It would seen more sensible to 
define work by the time a force is overcome. Could someone explain 
why work MUST be defined as Fx? How can holding a heavy weight for an 
hour not be considered work? Or, how can a spaceship not be doing 
work if it "fights" gravity, but using the same energy in space it 
would be doing work? Or, how can the earth's gravity give a falling 
object more and more energy per unit of time as it falls (as would be 
the case if the work equation is correct)? I hope someone will help 
me make sense of these "problems". Thanks.

Re: How can the equation for work (W=Fx) be proven?