Before writing about it first let me ask you this- How much time you spend to start doing some work ?
Answer: Too much.
Why waste time.Just as the heading suggest just do it means stop thinking about doing some work just do it.
Just dive in. Just do something. Just eat it. Just make some art. Just make a move. Just say hi. Just start asking people. Just start the story. Just begin the book.
Don't stop yourself by not knowing how to do a thing.Just start doing you will soon realize you have done it.
The moment you get an idea just write it on a paper , don't just think, write it first - whole idea.Then your work will be less to do the work.
SO what i just mean is if you will keep thinking whether you should a work or not, and more questions like this- you will end up doing nothing. So don't think just do it.