The poster for today is a bit cynical but the advice is not all that bad. Think about it in relation to where you are as a writer.
Sometimes, we reach a comfort zone. I know this editor will accept my submissions, so I'll just stay with her. That's great. We'd all like to have an editor who is our cheerleader and likes just about everything we send in. But it's not the case for the majority of writers. It's safe if we stay under the tree that we know best.
We have to continue to submit to our old markets but also find new ones. Years ago, writers had to go to the library to research markets in guides like the Writer's Digest published annually. Or purchase one each year. Today, we are so fortunate that we have the same kind of information online. Besides it being there, it takes very little effort on our part to pursue it. Just begin!
If you're like me, once you begin, you'll keep moving forward. It's kind of amazing the number of markets there are. Of course, we can eliminate many of them immediately as they publish genres we know nothing about. There is no way I could submit any of my work to a sci-fi magazine nor could I write a story in that field that would be worthy of being published, I know that, so I don't even try.
I also know the genres that I can write in and I stay with those. A Horror story writer is probably never going to get accepted by Chicken Soup for the Soul. Nor will a western short story writer find success sending work to a woman's fashion magazine.
I don't want to stay in one place and I doubt you do either, no matter how comfortable you think it is. We should aim for growth as a writer. Staying in one spot, like that tree, is not going to foster growth in any way. Step away from the sheltering branches of said tree. You might have to walk in the rain at times or you could move right into sunshine and roses. A bit of rain never hurt any of us, so don't be concerned what lies outside the comfort of the tree.
The key here is that it is up to you, nobody else, to make that first step away from your comfort zone. Last January, I took a deep breath and submitted to a high circulation magazine. I had serious doubts as to whether my writing was good enough for this highly-rated publication. Even so, I stepped away from my comfort tree and sent the story. Imagine the thrill I experienced when I received an acceptance a few weeks later. What if I'd never tried? It might have turned out that I received a rejection but at least I would have known that they read my work and sent me a letter.
You're not stuck in the ground in one spot. You can move in any direction you choose even if it is one step at a time.