The advice professional writers often give to aspiring writers is typically to write. Yes, obviously, people need to practice. And it is good advice, many people sit around wishing they could become a writer while they aren’t even trying to produce anything. So, yes, it is necessary to sit down and write, to force yourself to write even if you don’t feel inspired and feel like you don’t have anything to say, all to prepare for when you will have to do that as a professional. Waiting for inspiration to hit doesn’t work if you are writing for a paycheck.
That said it is also a gross over-simplification. Think about it like throwing darts. You could practice for hours every day but if your technique is not good then there will be an ability ceiling. You may be able to get pretty good doing it technically wrong, but you won’t get nearly as good as the people who practiced the correct way of doing it. Heck, they may not have even had to have worked nearly as hard to surpass you. And now that you’ve ingrained the wrong way of doing it you’ll now have even more trouble adjusting to doing it correctly.
Of course my advice is dependent upon your goal, if you’re only looking for how to get something sold and published then look to sources that talk about that. But if you’re also looking to have work that will be remembered and cherished then I have some words for you. It really doesn’t matter how brilliant a plot you have or what innovative way to tell it you have developed, the only way to make a story really endure is to endear it to people’s hearts, and that is accomplished through characters. It is through the characters that people get emotionally invested so that’s where you need to hit them. You probably should work on coming up with a number of different characters, explore their backgrounds in your daily writing exercise, and then find stories that you want to put them into. If you start from the plot and work backwards then you are fitting the characters to the story and that will be apparent. They will not feel natural or fully realized if they only exist within the confines of that story. Readers may not get anything more than that, but the characters need to have a life in your head. What this means is that there has to be more to the characters than just serving the plot, they have to have an internal reason for doing anything that they do. This is just one part of character building.
Characters also have to be differentiated. I know this seems obvious but quite frankly most writers don’t accomplish this. The test for the failure of character differentiation applies to everything from novels to comic strips, if the characters can be moved around in the story or if dialog can be swapped between characters with nothing seeming out of place then it has failed. Additionally the differentiation also has to be something readers can remember. The corollary test is to come up with a single sentence that defines the character, not their job or hobby or their part in the story, but something about them as an individual that marks them unique amongst the entire cast. This is what the reader will be doing in order to remember who someone is, especially in something with a larger cast, they'll try to ascribe a shorthand bio to each character to lock them in their memory. So I'm not saying you need to provide the shorthand bio for them, but you need to show the reader enough so that they can do that on their own.
Continuing along the idea of differentiation, the characters can't all think and feel the same way you do. First off, if they do then they won't be differentiated from each other which is a failure of what I just described above. Secondly, and I'm sorry to be the one to tell you this, but you just aren't interesting enough to carry the work forever. Sure you may be able to fake it for a short story or two, but never something deeper like a novel. The abilities to empathize with others and to be able to understand other people's perspectives are necessary skills to be a top quality writer. If you don't have those then you may as well go into writing movies for Uwe Boll and Michael Bay.
While writers tell you to write, readers, at least this one, want you to write about characters. The characters in the stories need to be equally as important as the plot, if not even more. Or you can just do forgettable stories, that’s perfectly fine. There are lots of people out there doing that for a living.