Don't start a blog. Post your thoughts on Facebook instead.
Don't write a book. Start a blog instead (see above).
Don't start a company. Work for as many different company's as possible instead.
Don't quit your job. Start planting seeds instead.
The thing is that the more friction you encounter when you start (and along the way), the higher the probability that you're a) never going to start or b) giving up after the first couple of setbacks.
Setting up a blog is hard. With hundreds of barriers. And setbacks. Posting updates on Facebook is easy.
Writing a book is hard. Formatting is hard. Everything about it is hard. Starting a blog is easy (see how to above).
Starting a company is hard. Trying to understand how companies work while building your own company is (almost) impossible. Learning how companies really work is a lot easier when you work for one.
Making cash right after you quit your job is (almost) impossible. Planting seeds while you still have a job and watching them grow into a strong enough tree is a lot easier.
It sounds very intuitive. And very straightforward.
Still, most people start the other way round and forget to eliminate major roadblocks. Most people start with the barrier. And the setbacks.
And when you start off facing a big fat dark wall, you'll never be able to see the light.
So people never really start. Or stop half way through.
At the end of the day it's all about getting rid of possible roadblocks. About taking that step back from that big fat dark wall so you can see that door and walk right through it instead of trying to jump over that wall.
And once you walked through that door, once you've got your first couple of small wins you can move on to the next step..