A job worth doing is worth doing well?

It means that if you can think of any task you think should be done, even if only out of necessity, then that task is worth your best effort. It could also mean that if there is something you have a strong desire to do but you just weren't born with the natural talent or ability to perform it, you should keep trying until you can do it well. You won't be productive in life at all if you won't put forth the effort to apply this saying to some extent.