There's no excuse for not writing - at least not very many really good ones.
You know, I think I see more people make excuses for why they can't write than I see people who make the effort to find half an hour in their day to jot down a few words. For that first group, everything is priority for them except for writing.
If you want writing to be a significant part of your life -- and future income -- then you have to adapt your thinking to include it. You can't have a 'oh, when I have time, I'll think about writing' attitude. Yes, there will always be important work that you must do first. Writing can't displace work and family. However, it shouldn't be the bottom of the list, somewhere after channel surfing for a couple hours to 'relax.' I know people who apparently take great joy in showing how much other stuff they can shove into their lives to avoid writing.
Look, bottom line: If you want to be a writer, you must write. More than just write a few lines here and there, jot down notes on a fantastic new character, think about the story you will write someday . . . when you find the time. Writing has to become important enough to you that you want to do it more than you want to sit in front of the television staring at something that doesn't even interest you. I don't mean you have to avoid your favorite shows -- however if you record them and speed-search through commercials, you'll already be gaining a significant amount of time back right there. Grab that time and apply it to writing.
Here's one more thought -- if you can't find even half an hour in your busy schedule to jot down a few lines and thoughts on your current work in progress, then maybe you seriously need to start restructuring your life anyway.
Everyone is busy. Most people can't find as much time for writing as they would like to have. The people who are serious, however, don't let that stop them from all writing.
If you make half an hour a day for writing, you will find that in that half hour you'll be able to write a few hundred words. It may take you a week or so before you get into the knack of it -- but once you have trained your brain to think 'half hour story time' you'll be surprised at how much writing-related work you can get done. You might even find it fun and rewarding enough that you expand it into a full hour.
We allow things to take up our time. We always have something on a list that we must do We'll fill that list every day; it's the kind of creatures we are. You consciously have to make room on the list for something new. I have seen people one day say they don't have time to write, and a few days later mention how they're taking up a new hobby. There is another indication that writing isn't getting the kind of recognition it needs. Those people are considering it less important than a new hobby.
If you are starting to see yourself in any of these descriptions, then you need to rethink your work as a writer.
Now some of you are thinking about how your muse can't be tied to a specific time, and how it would just be a waste of your time to set a schedule.
That's just more excuse making.
You are your muse. You are your inner editor. You are the writer. It's up to you to decide what you want to do. Maybe the angst part of not writing appeals to you. There are people out there who write far more about their writer's block than they will ever write of their fiction. They become addicted to the angst. Not all people with writer's block are in this situation, but it is often apparent which ones really are there just for the attention. If they could get a book published without the work and get the same amount of attention, they'd do it. This is just easier.
You have control over when and how you work. It may take you a while to get the knack of sitting down and working at a certain time. Give yourself small goals. Start with two hundred words. Those can be on the manuscript itself or on world building, characters or outline. You must make yourself write, though. You must put words on paper or screen. They must be words related to a writing project -- not notes about things you need to get done around the house.
You can do it. It's not as difficult as it sounds. You just have to want to give that much time to your writing. Maybe you really can't fit in half an hour every day -- but you should at least seriously consider trying before you say no.
There is no good reason to not do some writing every day. It doesn't have to be writing the fiction itself; you can work on world building, character creation or notes on your story idea. Eventually, it will add up to a story. You just have to be prepared to do the work, and not to make excuses to avoid it.