“Write with the door closed. Rewrite with the door open.” by Stephen King
The first question that comes up when I say "You should be writing" is "Who would want to read what I write?" And that's a valid question because why write something if no one is ever going to read it? Sure, you could scrawl away for hours a night in a million notebooks, but that's more "crazy person hatching plans" than "being a writer." When you are trying to write, you must remember the audience you are writing to.
So who is this mythical audience? To be honest, it could be anyone. When I sit down to write, I think about three people.
First and foremost, the first reader is always you. If what you are writing does not appeal to you day after day, either stop writing it and start something else or maybe try writing it from another angle. Notice I said day after day. One or two bad days of writing is normal. Not everything will come off gold and sometimes you will find yourself writing those scenes that you know you have to but would rather not.
Personally, I hate introductions, getting that first meeting of a character out of the way. But I know at some point my characters have to talk to somebody and they have to tell the audience who they are, so I try to trick myself into introducing characters in different ways. If you find it just is not your cup of tea after a few days or a few scenes, think about why. Listen to yourself. If you would not read it and can not come up with the passion to write it, best not struggle too hard at forcing it.
The second reader should be somebody or somebodies personally connected to you. This reader should like the same things you like, maybe enough to recommend your book if you had not written it. This is not an editor looking to cross all the t's and dot the i's. The draft you give this person should be at least a second or third with all the editing and grammar mistakes ironed out.
The second reader should be looking for tone and characters. Because they like the same stuff you do, listen when they say things like "I don't know why Bob is doing this" or "It doesn't seem like they have time to get to the spaceship." Rather than explain why or how the problem makes sense, realize that when your second reader asks questions it means you need to go back and explain those parts better. The second reader or readers are there to ask those questions so you do not have to go around to everyone who picks up your story and explain it to them.
The third reader is the public at large. Remember that no matter how much you had fun writing something, how much praise you got from your second reader, at some point you will have to let your little baby story go out into the world. Once a piece of writing is out in the world, out of your hands, it belongs to the world. Sure, you might get paid for it, own all the rights to it, but once people that do not know you read it they create a special relationship with it.
Any critique they give, any praise they give, ultimately is to the work itself and reflects back on you. So when you sit down to write, think back on the praise and critiques you have been given by the world and how you can use those to improve your writing.
If you don't have much reflection yet, then keep writing. You will soon.